71

http://www.ktvtrongquang.jimdo.com 2012

Editors: Freedberg, Irwin M.; Eisen, Arthur Z.; Wolff, Klaus; Austen,

K. Frank; Goldsmith, Lowell A.; Katz, Stephen I.

Title: Fitzpatrick's Dermatology in General Medicine, 6th Edition

Copyright Â©2003 McGraw-Hill

> Table of Contents > Part Three - Disorders Presenting in the Skin and

Mucous Membranes > Section 10 - Disorders of Epidermal Appendages and

Related Disorders > Chapter 71 - Hair

Chapter 71 Hair Elise A. Olsen

As with abnormalities of other organ systems, hair disorders can represent

either a primary or secondary dysfunction and can be related to exogenous

or endogenous causes. Hair is unique when compared to other organ

systems, however, in that it undergoes repetitive planned obsolescence and

rebirth, laying open the possibility of clinical disorders based on cycling

abnormalities. Further difficulties arise when the type and/or amount of

hair in a given body area deviates from the expected norm. The end result

of any of these abnormalities, either hair loss or overgrowth, often leads to

major psychological problems for patients.

This section on hair abnormalities reviews the primary causes of hair loss

and hair overgrowth and defines the significant pathophysiologic and

clinical features and therapeutic options of each.

HAIR CYCLE (See also Chap. 12)

Knowledge of the hair cycle is vital to understanding hair problems. The

duration and rate of growth of the anagen (growth) phase normally vary at

different body sites, in different individuals, and at various ages, and


determine the ultimate length of hair in that area.1 Catagen is the

transitional portion of the cycle between anagen and telogen and is short -

lived (2 to 4 weeks) in duration. Telogen duration also varies greatly in

different body sites, but interindividual variability appears more limited. In

a normal scalp, telogen is assumed to last 3 to 4 months and anagen to last

3-plus years. With age, there is both a diminution in anagen duration and an

increase in the time interval between two anagen cyc les.2 At any given

time, ~90 percent of the scalp hair is in anagen and 10 percent in telogen;

this is subject to some seasonal variability.3

At the end of anagen, each hair bulb moves from its location in the

subcutaneous tissue or dermis (depth of location is determined by whether

the follicle is terminal or vellus) to a more superficial location by means of

shrinkage and remolding of that portion of the follicle below the

â€œbulgeâ € where the arrector pili muscle inserts. The concentric layers

of the inner root sheath, which anchor the hair shaft in the follicle, are only

present to the bottom of the isthmus of the follicle, the region to which the

hair bulb ascends in telogen (Fig. 71-1). Consequently, the hair shaft in

telogen is no longer anchored securely in the tissue, as it was in anagen,

and it may be dislodged with the gentle traction of shampooing, combing,

brushing, etc. The recapitulation of the anagen follicle and initiation of

growth of a new anagen hair leads to the shedding of any remaining telogen

hair in the follicular canal (see Fig. 12-5).


FIGURE 71-1 Diagram of a normal anagen hair follicle.

DIAGNOSTIC TECHNIQUES

Techniques to Assess Cycling Abnormalities

There are several tools for determining aberrations of scalp hair cycling.

The first is the hair pull, which should be done on every patient with a

complaint of hair loss. This simple technique involves manually grasping a

group of 50 to 100 scalp hairs and applying gentle

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traction from the base to the terminal ends and repeating this in various

areas of the scalp.4 Normally, in the author's experience, only three to five

hairs total are dislodged on six to eight such hair pulls if the hair has been


shampooed regularly: shedding of more than three to five hairs per hair

pull is pathologic. This is a subjective test and results normally will vary

slightly in any given patient depending upon the physician performing the

test, each of whom may exert different degrees of traction on different sizes

of hair clumps. In the case of increased shedding, the proximal ends of the

hairs so obtained should be evaluated microscopically to determine whether

there is an intact hair shaft and bulb, indicating either an effluvium (Latin,

â€œa flowing outâ € ) or hair breakage. The hair bulbs should be further

evaluated to determine whether they are normal telogen (indicating a

physiologic aberration) versus dystrophic telogen or anagen hairs

(indicating a pathologic process).

There is litt le reason to do a hair pluck today. This momentarily painful

technique involves applying a clamp or needle holder to the base of 50 to

100 hairs and quickly pulling the hairs out en masse. Although this

technique, which is used in a trichogram, allows one to determine an

anagen/telogen ratio by inspection of the proximal hair bulbs, it fails to

give crit ical information about the type of hair being shed.

A third means of determining specifics regarding the hair cycle is the

phototrichogram .5 In this technique, hairs are clipped very short or shaved

in a given target area and comparative photographs are taken of the target

area at baseline and again 2 to 3 days later. As only the anagen hairs will

have increased their length on subsequent follow-up (normal hair growth is

~ 1 cm/month), this technique can be used to determine (1) the percentage

of hairs in anagen based on the number of longer hairs compared to total

hairs and (2) with sophisticated cameras and computer software, the hair

growth rate. To be reliable, a phototrichogram requires locating the same


precise target s ite at each time point, standardized photography, and

standardized hair counting by image analysis. A related procedure, called a

hair window, involves clipping or shaving the hairs in a given area and

having the patient return anywhere from 3 to 30 days later to evaluate

regrowth. Without photography, this is a gross technique for assessing the

potential for regrowth in a given area, and does not yield reliable

information regarding the specifics of cycling in the target area.

Biopsy

A biopsy of the scalp may or may not help with the diagnosis of a

particular hair disorder. The information it delivers about cycling

aberrations is merely confirmatory to that obtained by other simpler, less

expensive means, and the diagnosis of hair shaft abnormalities cannot be

made by a scalp biopsy. The real value of a scalp biopsy is the insight it

can offer into mechanisms of alopecia. A 4-mm punch biopsy is preferred

to a 3-mm one because of the ease of laboratory preparation and

accumulated quantifying data on normal scalp in the larger specimen. The

biopsy should be taken in the direction of the follicle growth and to a

sufficient depth to contain the follicular bulbs in anagen (generally into the

subcutaneous tissue). Vertical sectioning of the biopsy specimen gives an

immediate overview of the anatomy of the tissue from the epidermis down

to the fat, but unless multiple step sections are taken, the view is limited to

a snapshot of a few follicles. Horizontal (or transverse) sectioning of the

specimen gives a simultaneous overview of many follicles.6 This latter

technique requires sectioning at several different levels of the skin because

the terminal portion of the hair follicles will be at different depths

depending on the type (terminal versus vellus) of hair and part of the cycle


(anagen versus telogen) they are in, and because the pathology may lie

anywhere along the length of the follicle. Once appropriate sectioning is

done, however, all the follicles in a given horizontally sectioned biopsy can

be viewed simultaneously, giving a much greater amount of information

than is available from a similar number of vertical sections.

Hair Shaft Evaluation

The preferred hairs to examine in patients with a complaint of shedding are

those gently pulled from the scalp. This avoids the two major problems of a

hair pluck: physical distortion of the hair shaft by a clamp and the

distortion of all anagen hair bulbs so obtained. The proximal portions of the

collected hairs should be lined up on a slide in a drop of cyanoacrylic glue,

a coverslip applied, and the hairs viewed under light microscopy. Telogen

hairs have a cornified rounded-up bulb without an attached root sheath

(Fig. 71-2A). Anagen hairs are recognized clinically by their pigmented,

somewhat distorted, malleable bulb.

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Anagen hairs should not normally be found in a hair pull except in very

young childrenâ€”in this case, anagen hairs with an attached ruffled

cuticle, so-called loose anagen hairs (Fig. 71-2B), may be found in small

numbers, probably secondary to poor hair shaft anchoring to the root

sheath.7 Comparison with a normal anagen hair obtained by hair pluck is

shown in Fig. 71-2C .



FIGURE 71-2 A. Normal telogen hair obtained by hair pull. B. Loose

anagen hair obtained by hair pull; note the ruffled cuticle. C. Proximal end

of normal anagen hair obtained by hair pluck. D. Distal ends of newly

regrowing anagen hairs; note the tapered tips and comparative diameter

with established anagen hairs.

In those in whom the hair appears to be breaking off, â€œnot growing,â €

or unruly, the distal portion of the hair shaft should be evaluated. If a

fungal infection is suspected, potassium hydroxide (KOH) instead of glue

should be placed on the slide and the proximal hair examined for spores

and hyphae. The proximal hairs may need to be plucked from the scalp in

this case. In other situations, where a hair shaft disorder is suspected, a

gentle hair pull should be used to obtain hairs, but if no hairs are

forthcoming, then hairs should be cut, not plucked, for evaluation. A newly

growing anagen hair will have a tapered distal tip (Fig. 71-2D) rather than

the blunt distal end of hairs that have been cut or trimmed or in which the

ends are intrinsically broken. Most hair shaft abnormalities can be

diagnosed by light microscopic examination, although some types will

require further examination by scanning electron microscopy to confirm

findings only suggested by light microscopy (e.g., longitudinal grooving).

Polariscopic examination should be performed if trichoschisis (a particular

pattern of hair breakage) is seen under light microscopy in order to

evaluate potential trichothiodystrophy (sulfur-deficient hair).

The etiology of brittle hair can be further pursued by direct amino acid

analysis of whole-hair hydrolysates and electrophoretic characterization of

the main classes of proteins in hair (generally defined by their cysteine


content and designated ultrahigh-, high-, and low-cysteine or ultrahigh,

high-, and low-sulfur proteins).

ALOPECIA

To begin a discussion of hair loss or aberrant hair growth, it is useful to

have a means of organizing, rather than merely cataloguing the myriad

causes of alopecia. Deciding whether the hair loss is diffuse (global) or

focal (patchy or localized) can facilitate differentiation of the types of

alopecia. The following pathophysiologic categories can aid in further

defining the diffuse hair loss: (1) failure to produce or continue to produce

a normal hair follicle; (2) aberrations in the production of a normal hair

shaft; (3) aberration of the normal hair cycle; and (4) destruction of the

hair follicle. Determining whether the hair loss is a destructive or a

nondestructive process (clinically suggested by observing whether

follicular openings are preserved in areas of hair loss) can further narrow

the differential diagnosis. An approach that uses the aforementioned

diagnostic tools to aid in assignment of the hair loss process to one of these

categories is given in Table 71-1.


TABLE 71-1 Differential Diagnosis of Hair Loss


Diffuse (Global) Hair Loss

FAILURE OF FOLLICLE PRODUCTION

There has been a recent explosion of knowledge, largely fueled by null

mutant rodent models, regarding the genetic causes of diffuse alopecia

presenting in infancy and childhood. The most notable finding is the

abnormality of the human homologue of the mouse hairless (hr) gene,

which causes congenital universal atrichia and atrichia with papular

lesions .8,9 and 10 The atrichia may be present from birth or develop over

the first year of life: this is concordant with an abnormality in

recapitulation of the anagen follicle after the first pelage as seen in hairless

knockout mice. The patients with atrichia with papular lesions develop

follicular cysts, generally 3 to 18 years after the alopecia (Fig. 71-3). The

hairless gene product is a putative multifunctional transcription factor and

the gene locus is on chromosome 8p12. A similar clinical phenotype with

universal hair loss during the first year of life and cutaneous cysts years

later but

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accompanied by rachitic bones is seen in hereditary vitamin D-resistant

rickets .11 This condition is secondary to mutations in the vitamin D

receptor, probably in the zinc finger domain, which, like the hr gene, acts

as a transcription factor. Patients previously diagnosed with alopecia

universalis (alopecia areata) at birth or few months of age may, in fact,

have one of the conditions noted above, particularly if the universal hair

loss is persistent and/or familial.


FIGURE 71-3 Atrichia with papular lesions. (Photograph courtesy of

Abraham Zlotogorski, MD.)

HAIR SHAFT ABNORMALITIES

Diffuse hair loss in infancy is more commonly one of hypotrichosis than

total atrichia and may be secondary to abnormal production of a subset of

hair follicles and/or hair shafts. Most of the hereditary alopecias do not

occur alone but in the company of a constellation of other anomalies, most

frequently bone, central nervous system, or eye. Freire-Maia has suggested

a classification system for those hereditary disorders of ectodermally


derived tissue that demonstrate a primary abnormality of two of the

following: hair, teeth, nails, or eccrine glands: these are termed type A

ectodermal dysplasias .12 An abnormality of one of these four major

anomalies plus one other â€œectodermalâ € sign is termed type B

ectodermal dysplasia . Those ectodermal dysplasias that involve hair have

been further catalogued in the available detail by Olsen using the

classification system of type A ectodermal dysplasias.13 Most reported

syndromes that involve hair are also discussed and regularly updated,

including genetic information, in McKusick's Mendelian Inheritance in

Man.14 These three sources facilitate the diagnosis of hereditary childhood

alopecias.

Hair shaft abnormalities can be primary and hereditary or secondary to

external factors. Some hair shaft abnormalities represent common endpoints

to various forms of trauma or inherent shaft weaknesses, and some are

specific to a particular constellation of findings or inherent make-up of the

hair shaft. Hair shaft abnormalities can be divided into those associated

with hair breakage and those associated with unruly hair.

Hair shaft abnormalities associated with hair breakage

TRICHORRHEXIS NODOSA

The most common defect of the hair shaft leading to hair breakage is

trichorrhexis nodosa.15 Mechanical or chemical damage triggers this

response, which can occur in normal hair, but occurs much more readily in

inherently weak hair. Microscopically, the affected hair develops a breach

in the cuticle, with eventual separation and fraying of the exposed cortical

fibers leading to a nodal swelling.16 The fibers then fracture and the shaft


breaks with the resultant appearance of a splayed paintbrush or fanlike

array (Fig. 71-4). Trichorrhexis nodosa may be congenital or acquired.

FIGURE 71-4 Trichorrhexis nodosa.

Congenital trichorrhexis nodosa may be present at birth or may appear

within the first few months of life. Although it might occur as an isolated

defect or, rarely, with follicular hyperkeratosis or teeth/nail defects,15 the

occurrence of congenital trichorrhexis nodosa should lead to a search for an

underlying metabolic disorder. Patients with argininosuccinic aciduria,

primarily those with the late-onset form (occurring at >2 years of age),15

have associated hair defects. In this condition, in which absence of the

enzyme argininosuccinase leads to an accumulation of the nitrogenous

waste precursor argininosuccinic acid, brittle lusterless hair develops along

with psychomotor retardation and ataxia. The diagnosis is established by


finding acidosis, hyperammonemia, and low serum arginine.17 Citrulline

(the normal precursor of argininosuccinic acid in the urea cycle)

accumulates in the condition citrullinemia, which is caused by a defect in

the enzyme argininosuccinic acid synthetase. In this condition, the hair is

brittle and both trichorrhexis nodosa and pili torti (another common hair

shaft defect) may be present.15,18 Affected infants have an associated

dermatitis that may be widespread but more pronounced in the perioral and

diaper area. Patients with Menkes syndrome, caused by a defect in copper

efflux,19 and trichothiodystrophy, caused by a defect in the synthesis of the

ultrahigh- and high-sulfur proteins integral to hair,20 both have

trichorrhexis nodosa apparent on microscopic examination of the associated

brittle hair.

Acquired trichorrhexis nodosa may be either distal or proximal. Proximal

breakage appears most commonly in African-American women, usually

after repetitive chemical or hot-comb straightening.15 Distal trichorrhexis

nodosa is more commonly secondary to excessive brushing, back-combing,

or sporadic use of permanent waves.

Treatment of trichorrhexis nodosa, congenital or acquired, is by avoidance

of chemical or physical trauma to the hair.

TRICHOSCHISIS

The break in trichoschisis is a clean transverse fracture through the entire

hair shaft at a location where there is a focal absence of cuticle (Fig. 71-

5A). Trichoschisis is usually, but not specifically, a marker for the sulfur-

deficient hair of trichothiodystrophy, in which the hairs of the scalp,

eyelashes, and brows are short and brittle.15 The hair abnormality of

trichothiodystrophy identifies a group of autosomal recessive disorders in


which acronyms or eponyms identify particular constellations of

extratrichologic neuroectodermal abnormalities (Table 71-2). In affected

individuals, the hair cystine

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content is less than half normal, primarily from a major reduction and

altered composition of the ultrahigh-sulfur matrix proteins.20 Polariscopic

examination of affected hairs characteristically shows alternating light and

dark bands, presumably secondary to variations in sulfur content15 (Fig.

71-5B). Sulfur and/or amino acid analysis of the hair is diagnostic.

TABLE 71-2 Trichothiodystrophy


FIGURE 71-5 Trichothiodystrophy. A. Hair shaft with trichoschisis without

polarization (light micrograph Ã—100). B. Hair shaft with polarization

(light micrograph Ã—100). (From Whiting,15 with permission.)

Patients with trichothiodystrophy, particularly the 50 percent with

associated photosensitivity, may have a defect in excision repair of

ultraviolet damage but without an increased risk of skin cancer.21 Recent

data support correlation of mutations in the DNA repair and transcription

gene ERCC2 locus with the nucleotide excision repair characteristics of

both trichothiodystrophy and xeroderma pigmentosa.22 No treatment is

currently available, but photosensitive patients should be tested for their

cellular response to ultraviolet radiation and encouraged to practice sun

protection.


PILI TORTI

The short and brittle hairs in patients with pili torti, when viewed through a

microscope, appear flattened and twisted through 90Â° to 360Â°.15 The

twisting must be differentiated from the normal twisting seen in Negroid

hair and in the pubic/axillary hairs of other races; the hairs are

distinguished by the multiple irregular intervals of twisting along an

otherwise straight hair shaft (Fig. 71-6A).


FIGURE 71-6 Pili torti. A. Irregularly spaced 180Â° twists in hair shaft.

(From Whiting,15 with permission.) B. Brittle broken hair typical of

congenital pili torti.

As with trichorrhexis nodosa, pili torti does not signify a particular

abnormality but can be seen in many different syndromes and in the

presence of other hair shaft abnormalities. Hereditary pili torti as an

isolated finding, usually autosomal dominant, but potentially autosomal

recessive or sporadic, is present at birth or develops over the first 2 years

of life (Fig. 71-6B). Clinically, the patient may have patchy alopecia with

coarse stubble or longer broken hairs. The hair abnormality may improve

after puberty.

Pili torti, or a facsimile best characterized as â€œtwisting hair

dystrophy,â € 23 may occur with other abnormalities (Table 71-3).

Particularly notable is the association of pili torti with Menkes' syndrome

or trichopoliodystrophy . Infants with Menkes ' syndrome develop sparse,

depigmented brittle hairs that show pili torti or trichorrhexis nodosa on

microscopic examination.15 The affected child characteristically has pale,

lax skin, and mental and neurologic impairment secondary to degeneration

of cerebral, cerebellar, and connective tissue.24 In this X-linked recessive

disorder, the defective gene, MKN or ATP7A, which maps to Xq13.3,

encodes a copper-translocating membrane protein ATPase that prevents

effective copper transport and leads to the accumulation of intracellular

copper in some tissues.19 The excessive intracellular copper

inappropriately triggers the synthesis of metallothionein, whose normal

function is to chelate copper to prevent cellular toxicity. This further


deprives the copper-requiring enzymes of the copper needed for normal

function.25 A low serum level of ceruloplasmin is diagnostic. Copper

replacement is ineffective in preventing the inevitable progressive and

lethal neurologic decline, but copper-histidine given immediately

postpartum may prevent or ameliorate the severe neurodegeneration.26


TABLE 71-3 Causes of Telogen Effluvium

TRICHORRHEXIS INVAGINATA


Trichorrhexis invaginata (â€œbamboo hairâ € ) is a distinctive hair shaft

abnormality that may occur sporadically, either in normal hair or with other

hair shaft abnormalities, or regularly as a marker for Netherton's syndrome.

The primary defect appears to be abnormal keratinization of the hair shaft

in the keratogenous zone, allowing intussusception of the fully keratinized

and hard distal shaft into the incompletely keratinized and soft proximal

portion of the shaft.27 This leads to the typical â€œball-and-socketâ €

deformity (Fig. 71-7) or, if fracture of the shaft occurs, a golf tee-shaped

distal end of the shaft.

FIGURE 71-7 Trichorrhexis invaginata (light micrograph Ã—400). (From

Whiting,15 with permission.)

Netherton's syndrome (see Chap. 51) is an autosomal recessive inherited

disorder consisting of a triad of ichthyosis, atopic diathesis, and

trichorrhexis invaginata.15 Affected hairs are generally short and


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brittle and may be irregularly distributed over the scalp; this may lead to

potential sampling errors on hair shaft evaluation. The ichthyosis is usually

polycyclic ichthyosis linearis circumflexa but may be lamellar ichthyosis or

even ichthyosis vulgaris or X-linked ichthyosis. The atopic diathesis may

include erythroderma. Recurrent infections, short stature, and mental

retardation are rarely reported with Netherton's syndrome. The Netherton's

syndrome gene product is LEKTI, a serine protease inhibitor; the gene

(SPINK5) locus is chromosome 5q32.28 Retinoids and phototherapy may be

of value, although the condition may improve spontaneously over time.

MONILETHRIX

The hair abnormality of monilethrix is distinctive, with extremely short,

brittle hairs emerging from keratotic follicular papules29 (Fig. 71-8A). The

onset may be delayed until patients are in their teens, and the loss may be

localized or diffuse. Microscopically, hairs show elliptical nodes with a

regular periodicity of 0.7 to 1 mm.15 Between the nodes, the hair shaft is

constricted, and it is in these areas that the hair usually fractures (Fig 71-

8B). The disorder is caused by mutations in the genes for type II hair

keratins hHb1 or hHb6 in the type II keratin gene cluster on chromosome

12q13.30,31 Both hHb1 and hHb6 are expressed in the hair cortex cells

with the abnormality in the helix termination or initiation motifs.30


FIGURE 71-8 Monilethrix. A. Keratotic papules in areas of alopecia. B.

Typical beaded appearance of hair as seen under light microscopy (Ã—40).

(From Whiting,15 with permission.)

Most cases of monilethrix are of autosomal dominant inheritance, with

variable expressivityâ€”the hair defect can be mild and localized to the

occiput.15,31 The hair defect may occur alone or in association with


keratosis pilaris, physical retardation, syndactyly, cataracts, and nail/teeth

abnormalities. Retinoids and topical minoxidil may be useful treatments,

although this condition may also improve spontaneously with age.

Hair shaft abnormalities associated with unruly hair

UNCOMBABLE HAIR SYNDROME

The distinctive hair of patients with uncombable hair syndrome may

present any time from infancy to puberty. The slow-growing, silvery

blonde, â€œspun-glassâ € hair is generally unmanageable and disorderly

but not unduly fragile15,32 (Fig. 71-9A). The condition may be autosomal

dominant or sporadic. Under light microscopy, the hair appears normal or

may have some suggestion of a longitudinal groove or ribbon-like

flattening (Fig. 71-9B). Scanning electron microscopy confirms a

longitudinal groove, and the hair may, if viewed on cross-section, show a

kidney bean or triangular shape, which accounts for the alternate term of

pili trianguli et canaliculi . The longitudinal groove in the hair shaft is not

specific to this syndrome but can be seen in normal hair, in other etiologies

of unruly hair, and in several types of ectodermal dysplasia.15 The defect

may be secondary to an abnormal configuration of the inner root sheath,

which keratinizes before the hair shaft and thus determines its shape.32

Biotin supplementation has been advocated in one case report,33 but

generally there is no effective treatment for the syndrome.


FIGURE 71-9 Uncombable hair syndrome. A. Typical clinical picture.


(Photograph courtesy of Vera H. Price, MD.) B. Longitudinal groove seen

in uncombable hair syndrome (light micrograph Ã—400). (From Whiting,15

with permission.)

WOOLY HAIR

Wooly hair is the presence of Negroid hair on the scalp of persons of non-

Negroid background. Microscopically, the hairs are tightly coiled. The

unruly hair presents at birth or in infancy, usually as a solitary problem

inherited in an autosomal dominant fashion.34 However, two families with

either autosomal dominant or autosomal recessive inheritance and

associated palmoplantar keratoderma and cardiac abnormalities have been

reported.35 A sporadic variant has been reported with fine white-blond hair

(Fig. 71-10). Diffuse partial wooly hair, a recently described autosomal

dominant condition, presents in young adulthood with two distinct

populations of scalp hair, one straight and the other very curly.36 The curly

hairs are thinner than normal hairs, which may contribute to the clinical

appearance of a reduction in hair density.


FIGURE 71-10 Sporadic recessive wooly hair.

MARIA-UNNA TYPE OF HEREDITARY HYPOTRICHOSIS

This autosomal dominant condition is unusual in that the hair abnormality

varies with age. The scalp hair in Maria-Unna type of hereditary

hypotrichosis is sparse or absent at birth, with variable coarse, wiry hair

regrowth in childhood, and potential loss again at puberty.37 Body hair is

sparse to absent. Light microscopic examination of the hairs shows

irregular twisting, and scanning electron microscopic examination shows

longitudinal ridging and cuticle peeling. Diffuse follicular hyperkeratosis

and facial milia-like lesions may be present. A distinct gene in

chromosomal region 8p21 close to the hairless (hr) locus has been noted.38

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Hair shaft abnormalities unassociated with breakage or unruly hair

There are a few specific abnormalities of the shaft that should be noted

here because of their frequency. The hair in pili annulati, an autosomal

dominant (occasionally sporadic) condition, shows alternating light and

dark bands both clinically and under light microscopy secondary to air-

filled spaces in the cortex.39 Cuticle folding and holes in the cortex are

seen with electron microscopy.15 Clinically, the hair in pseudo pili

annulati shows a similar light microscopic picture, but the condition is

nonhereditary and is not associated with any hair shaft cortex

abnormality.40 The cause of the latter appears to be periodic flattening of

the hair shaft that causes light to be reflected as bright bands.

Both conditions appear primarily in blond hair and are not associated with

hair breakage. With transverse illumination, the banding in pili annulati is

seen in whatever way light strikes the hair, whereas pseudo pili annulati is

seen only when the hair is rotated into certain positions.39

ABNORMALITIES OF HAIR CYCLING

Telogen effluvium

This common type of hair loss may occur at any age and represents a

precipitous shift of a percentage of anagen hairs to telogen. Telogen

effluvium is a reaction pattern to a variety of physical or mental stressors;

the most common causative factors are given in Table 71-3. Any drug can

potentially cause telogen effluvium, although some classes of drugs

routinely cause this.


The clinical increase in scalp hair shedding (over a normal of 50 to 100

hairs per day) usually begins as the first group of anagen hairs to be thrown

prematurely into telogen finally completes telogen and moves once again

into anagen, 3 to 4 months after the inciting event. If the inciting cause is

removed the shedding will resolve over the next several months as the

percentage of hairs in telogen return to normal; however, the hair density

may take 6 to 12 months to return to baseline. In a significant number of

patients, no obvious cause is found for telogen effluvium, and the increased

shedding, and concomitantly the decreased density, of the scalp hair may

become chronic.41 Telogen effluvium is always potentially reversible and

does not lead to total scalp hair loss, as the percentage of hairs in telogen

rarely goes beyond 50 percent (Fig. 71-11).

FIGURE 71-11 Telogen effluvium.

Anagen effluvium


The daily loss of some telogen hairs is entirely normal, but it is always

abnormal to shed anagen hairs. The term anagen effluvium, as currently

used to describe the pathologic loss of anagen hairs, is somewhat

misleading because the abnormal anagen hairs in this condition are usually

broken off rather than shed. The anagen hairs in loose anagen syndrome,

however, are shed in toto.

The classic and easily recognizable causes of anagen effluvium of the scalp

are radiation therapy to the head and systemic chemotherapy,

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especially with alkylating agents. These agents can impair or totally disrupt

the anagen cycle. The net result is either anagen hairs that break off within

the follicle or at the level of the scalp secondary to a weak point in the hair

shaft and are then shed without roots, or dystrophic anagen hairs that are

easily dislodged from the usual follicular moorings. Replacement with a

normal pelage usually occurs rapidly after discontinuation of chemotherapy

although high-dose busulfan as part of the preparatory treatment for bone

marrow transplantation may lead to permanent alopecia.42 Regrowth after

radiation therapy depends on type, depth, and dose-fractionation.43

In the absence of these obvious causes of anagen disruption, one must

consider exposure to toxic agents. Mercury intoxication, through either

chronic industrial exposure, consumption of polluted water or seafood, or

inadvertent exposure to mercury-containing antiseptics or fungicides, can

lead to hair loss with or without other symptoms, especially neurologic

ones.44 Diagnosis is by documenting elevated mercury levels in hair,

blood, or urine. Boric acid intoxication may be through exposure to


household pesticides or ingestion of some common household products in

which boric acid is a preservative. Patients may develop hair loss along

with gastrointestinal, central nervous system, and renal symptoms, a

hemorrhagic diathesis, and exfoliation or bullae.43,45 Blood boric acid

levels are elevated in affected patients.

Thallium poisoning has the most dramatic associated hair loss, with

complete epilation occurring 2 to 3 weeks after intoxication.46 Acutely,

patients experience primarily neurologic symptoms including irritability,

dysesthesia, ataxia, convulsions and coma. Blood and urine levels are

positive at the time of acute poisoning.

Toxic exposure to colchicine and ingestion of certain plants can lead to

anagen loss.43 Severe protein malnutrition may also lead to anagen

effluvium. Arsenic exposure does not cause hair loss; instead, arsenic is

concentrated in the hair, which facilitates a diagnosis long after

intoxication may have occurred.

Loose anagen syndrome

This recently described syndrome has been primarily described in fair-

haired children who have easily dislodgable hair (Fig. 71-12A).47,48

However, loose anagen syndrome can occur in adults and may be familial.

This condition can be, and probably previously was, misdiagnosed as

telogen effluvium if the shed hair roots are not examined microscopically.

The hair loss may be inapparent except when traumatic pulling or

extraction easily dislodges clumps of hair; this is particularly so in the

parents of affected children, who themselves may have a mild, but

previously unrecognized, variant of the condition that clinically may appear

indistinguishable from a mild persistent telogen effluvium. The hair may


also present with unruliness, occasionally causing confusion with

uncombable hair syndrome or wooly hair (Fig. 71-12B). Microscopically,

the proximal shed hair shows a normal anagen bulb, with a ruffled cuticle

but without the usual attached root sheath7 (see Fig. 71-2B). A scalp

biopsy, which is unnecessary for diagnosis, may show premature and

abnormal keratinization of the inner root sheath, with clefts between the

inner and outer sheath and the hair shaft. The hair loss may improve with

age, and gentle handling decreases shedding.



FIGURE 71-12 Loose anagen syndrome. A. Diffuse hair loss. B. Unruly

hair. (From Olsen,7 with permission.)

Alopecia areata

At any given time, approximately 0.2 percent of the population has alopecia

areata and approximately 1.7 percent of the population will experience an

episode of alopecia areata during their lifetime.49,50 Clinically, patients

with alopecia areata may have patchy or confluent hair loss on the scalp

and/or body (Fig. 71-13A). Alopecia totalis refers to the total absence of

terminal scalp hair, and alopecia universalis refers to the total loss of

terminal body and scalp hair.51 Ophiasis refers to a bandlike pattern of hair

loss over the periphery of the scalp (Fig 71-13B). Hair loss may also be

diffuse, mimicking anagen effluvium (Fig. 71-13C).



FIGURE 71-13 A. Extensive patchy alopecia areata. B. Ophiasis pattern of

alopecia areata. C. Diffuse pattern of loss in alopecia areata. (Reprinted

with permission from Hardinsky MK: Alopecia areata, in Disorders of Hair

Growth: Diagnosis and Treatment, edited by EA Olsen. New York, McGraw-

Hill, 1994.)

The scalp appears normal in alopecia areata. In affected areas, anagen is

abruptly terminated prematurely and affected hairs move prematurely into

telogen, with resultant often precipitous hair shedding. The near

pathognomonic â€œexclamation pointâ € hairs may be present,

particularly at the periphery of areas of hair loss (Fig. 71-14). These short

broken hairs, whose distal ends are broader than the proximal ends,

illustrate their inherent sequence of events: follicular damage in anagen and

then a rapid transformation to telogen. White or graying hairs are

frequently spared and probably account, in cases of fulminant alopecia

areata, for the mysterious phenomenon of â€œgoing gray overnight.â €

There is an increased incidence of autoimmune diseases in patients with

alopecia areata, particularly thyroid-related disease,52 and there is a higher

prevalence of pigmentary defects in patients with alopecia areata.53 Nails

in patients with alopecia areata may show fine pitting or, less commonly,

mottled lunula, trachyonychia, or onychomadesis.54


FIGURE 71-14 Exclamation mark hairs of alopecia areata. (From Olsen

EA: Clinical tools for assessing hair loss, in Disorders of Hair Growth:

Diagnosis and Treatment, edited by EA Olsen, New York, McGraw-Hill,

1994, with permission.)

A scalp biopsy is generally unnecessary to establish the diagnosis of

alopecia areata, except in the uncommon presentation of diffuse shedding

in which telogen or anagen effluvium is also a consideration. Typically, a

biopsy of involved scalp shows a peribulbar, perivascular, and outer root

sheath mononuclear cell infiltrate of T cells and macrophages.55 Follicular

dystrophy, including abnormal pigmentation and matrix degeneration, may

also be present.56


The pathogenesis of alopecia areata is still obscure, although most authors

tend to classify alopecia areata as an autoimmune disease. As opposed to

normal hairs, strong major histocompatibility complex (MHC)

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class I and class II immunoreactivity are found in lesional alopecia areata

follicles, which also display aberrant expression of adhesion molecules

known to direct hematopoietic cell migration.54 One potential explanation

for the failure of repression of MHC expression necessary for autoimmunity

to develop in alopecia areata is the release of cytokines by certain stimuli,

including trauma, neurogenic inflammation, or infectious agents. The

elusive follicular autoantigens so exposed may be of keratinocyte or

melanocyte origin, but the almost exclusive attack on melanogenically

active anagen follicles makes this a particularly attractive hypothesis. That

there is a genetic association with both susceptibility to and severity of

alopecia areata is clearly shown by recent human leukocyte antigen (HLA)

studies.57

Spontaneous remission is common in patchy alopecia areata, but is less so

with alopecia totalis or universalis.52 Spontaneous or treatment-related

regrowth is also adversely affected by the location of hair loss (ophiasis

pattern is particularly recalcitrant), the age of onset (children younger than

5 years old with alopecia totalis or universalis have the worse prognosis),

association of atopy, and duration of hair loss in a given area.52,58 Current

treatment is not, at this point, directed at the etiology of alopecia areata but

rather at the resulting inflammatory infiltrate and (presumably) the growth


inhibitory factors produced by this response. Relapse is common, both

acutely and over a lifetime.

Treatment of alopecia areata is with either immunosuppressives (local or

systemic) or with irritants/immunogens, and is generally tailored to the

severity of the disease.54 For localized patchy alopecia areata, intralesional

steroids given at 4- to 6-week intervals are usually effective, with the main

side effect being local dermal/subcutaneous atrophy related to the depth

and concentration of injected steroid. Topical glucocorticoids classes I to V

are also effective but take several months for initiation of hair growth,

rather than the weeks for intralesional steroids. Side effects of topical

steroids are generally limited to acne/hypertrichosis on the face from

inadvertent transfer from the scalp and local epidermal atrophy with the

more potent steroids. Systemic steroids, particularly short courses (less

than 8 weeks) of tapering doses, are often used either alone or in

conjunction with topical agents. In this setting, acne and weight gain are

commonly seen side effects.59 PUVA is another immunosuppressant

treatment that may be effective in alopecia areata, particularly in patients

with extensive scalp and body hair loss. Between 30 and 80 treatments may

be necessary before hair induction occurs, and there is an increased risk of

photodamage/photoaging and skin cancer with PUVA use.60

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The immunostimulation of topical irritants, especially anthralin, or topical

immunogens (diphencyprone, squaric acid dibutylester) can be very

effective in alopecia areata, but their use runs the risk of intolerable


irritation if the dose titration is inappropriate. The particular mechanism of

action of contact dermatitis that makes it a treatment for alopecia areata is

purely speculative at this time, but it may include enhanced clearance of

the putative follicular antigens through recruitment of new T cells and

antigenic competition and interference with the initial or continued

production of proinflammatory cytokines by the follicular keratinocytes.61

Five percent topical minoxidil, as a nonspecific hair growth promoter, may

be a useful drug as a single agent or as an adjuvant with topical

anthralin.62 There is a low incidence of local dryness/irritation and facial

hypertrichosis with topical minoxidil. Although rare, the potential for

systemic effects of topical minoxidil, particularly in young children, must

be considered and the total amount applied kept to the recommended â‰¤ 2

mL/day.

Patients with alopecia areata need psychological support and physical

means of camouflaging their hair loss. The latter often requires the use of a

wig, which should be considered an integral part of treatment in patients

with extensive scalp hair loss. The National Alopecia Areata Foundation is

an excellent source of information for patients (www.naaf.org).

Focal Hair Loss

NONSCARRING HAIR LOSS

Production decline

TRIANGULAR (TEMPORAL) ALOPECIA

Triangular alopecia may be congenital but usually appears in childhood as

a focal patch of hair loss. The hair loss either may be complete or fine

vellus hairs may remain.13,63 The underlying scalp is normal. The

temporal region is a common location, and the hair loss is frequently


bilateral (Fig. 71-15). Histologically, the affected area shows a transition

from terminal to vellus hair. The alopecia is usually persistent.

FIGURE 71-15 Triangular alopecia.

PATTERN HAIR LOSS

The term androgenetic alopecia was previously applied to both men and

women with a very common, potentially reversible scalp hair loss that

generally spares the â€œHippocratic wreathâ € portion of the scalp. The

hair loss condition in men and women has in common miniaturization and

shortening of anagen duration of affected hairs and, consequently, an

increased percentage of affected hairs in telogen.64,65 Men with this type

of alopecia tend to have somewhat synchronous behavior of hairs in the

four different regions of the top of the scalp (vertex, mid, frontal, and

bitemporal) along with potentially profound degrees of miniaturization

leading to recognizable patterns of hair loss (Fig. 71-16).65 In men, this


male pattern baldness is hereditary (probably autosomal dominant) and

androgen dependent, specifically dihydrotestosterone-related.64,66



FIGURE 71-16 Hamilton-Norwood classification of pattern hair loss in

men. (From Olsen,65 with permission.)

Women, on the other hand, have lesser degrees of miniaturization of

terminal hairs in affected areas and, hence, rarely any â€œbaldingâ € when

compared to men. Patterning is less obvious then in men, although three

patterns of hair loss do exist in women (Fig. 71-17A, Fig. 71-17B).65 Not

all women with pattern hair loss have proven androgen-dependence. Women

with profound hyperandrogenemia, which is usually tumor related, may

develop a Hamilton pattern of hair loss or severe diffuse central scalp hair

loss, and women with other stigmata of

hyperandrogenemia/hypersensitivity, such as those with polycystic ovarian

syndrome, may present with pattern hair loss in the second to third

decades.65 The majority of women with pattern hair loss, however, have no

increase in serum androgens, no other signs/symptoms of androgen

hypersensitivity, and do not respond to androgen inhibition with reversal of

hair loss.64,65 Therefore, the preferred more encompassing

â€œumbrellaâ € term for this hair loss in women is female pattern hair

loss . Subcategories of â€œearly onset female pattern hair loss with or

without androgen excessâ € and â€œlate postmenopausal onset female

pattern hair loss with or without androgen excessâ € 65 will allow sorting

out of the genetic (e.g., polycystic

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ovarian syndrome and early male pattern baldness appear genetically

linked)67 and cellular mechanisms of these various subtypes.


FIGURE 71-17 Pattern hair loss in women. A. Different phenotypic

expressions. B. Characteristic frontal accentuation.

Androgen-mediated hair growth (or loss) requires formation of an

androgen-androgen receptor complex, which then binds to the androgen-

response element DNA-binding site leading, in turn, to transcription of


certain protein(s).64 Androgens are 19-carbon steroid structures (Fig. 71-

18), that are normally produced by both adrenal glands and gonads. The

most potent androgens (testosterone, dihydrotestosterone, and

androstenediol) are those with a 17-hydroxy group, as this moiety is

necessary for high-affinity androgen receptor binding. The weaker 17-

ketosteroids, such as dehydroepiandrosterone and androstenedione, assume

importance by their interconversion by 17-OH steroid dehydrogenase to

more potent androgens at the end-organ site, including the hair follicle. The

enzyme 5Î±-reductase converts testosterone to dihydrotestosterone, which

has greater affinity and avidity for the androgen receptor.68 Two isozymes

of 5Î±-reductase, called 5Î±R1 and 5Î±R2, have been cloned and their

corresponding genes are located on chromosomes 5 and 2 respectively.66

Although type I 5Î±-reductase appears to be more ubiquitously distributed

in skin, particularly in the sebaceous gland, 5Î±-reductase type 2 is found

in the outer root sheath69 and dermal papillae of hair follicles, but is

differentially expressed in various tissues.64 That 5Î±-reductase type 2 is

involved in male pattern baldness is suggested by the absence of balding in

men with 5Î±-reductase type 2 deficiency;66 the increased expression of

5Î±-reductase in balding versus nonbalding scalp;70 the results in animal

models of androgenetic alopecia showing reversal of hair loss with type 2

but not type 1 5Î±-reductase inhibitors;64 and the response of men with

male pattern baldness to finasteride, an inhibitor of 5Î±-reductase type 2.71


FIGURE 71-18 Androgen pathway. (From Kaufman,66 with permission.)

Effective treatment of pattern hair loss in both men and women can include

both medical and surgical approaches. Topical minoxidil (2% and 5%) is a

nonspecific hair-growth promoter affecting anagen induction, duration, and

size of hair shaft. Although the mechanism of action in hair growth

promotion is unclear, its calcium channel opener activity appears to be

important.64 The medication should be applied to the scalp twice a day,

with the earliest clinical response seen at 4 to 6 months and generally a

maximum response at 1 year.64 About 20 to 25 percent of persons so

treated will have notable clinical regrowth, although most patients will

experience at least a stabilization of loss.72 There is slight risk of facial

hypertrichosis and of irritation/allergic contact dermatitis, secondary to


either the minoxidil or propylene glycol. Both side effects are more

frequent with the 5% versus the 2% preparation.64 Whether the facial

hypertrichosis is from inadvertent transfer from the scalp or secondary to a

local reaction to low levels of serum minoxidil is not clear.

Surgical treatment of pattern hair loss has undergone dramatic improvement

in recent years73 (see Chap. 277). It is based on the premise of â€œdonor

dominanceâ € whereby hairs from a nonandrogen-dependent site (occiput)

can be successfully transplanted to a bald androgen-dependent site.

Cosmetic coverage is currently limited by the amount and density of

available occipital donor hair and the expertise of the surgeon. Ideally,

male candidates for this procedure should be those in whom final

resculpturing of the frontal hair line has naturally occurred. A combination

of minigrafts (1.5- to 2.5-mm grafts) and micrografts (one to two hairs each

graft) of donor hair are used more frequently now than the once standard 4-

mm plugs to fill in areas of baldness. The micrografts are particularly

useful because they do not require removal of a plug of tissue into which to

insert the graft; rather, a small hole or incision can be made to

accommodate a single or a few donor hairs. Micrografting is the surgical

treatment of choice in women with pattern hair loss, who, unlike men,

never develop baldness and for whom the use of standard hair transplants

means sacrificing terminal hair when a recipient plug of tissue is removed.

For women with pattern hair loss, at least those who have documented

androgen excess or androgen hypersensitivity, the use of medications that

block either the production of or the cellular utilization of androgens may

be helpful. Although the systemic antiandrogens spironolactone (in doses

â‰¥ 100 mg daily),74 flutamide (in doses of 250 to 500 mg bid to tid),75


and cyproterone acetate76 have shown some effectiveness in women with

pattern hair loss, none of these have been studied in large placebo-

controlled trials or with stratification of women by presence or absence of

hyperandrogenism. This is especially important today because there is a

lower threshold, given our knowledge of coincident insulin resistance, to

identify polycystic ovarian syndrome, a potential cause of

hyperandrogenism and concomitant pattern hair loss.

Spironolactone is a potassium-sparing diuretic whose main side effects are

hyperkalemia, irregular menses, and breast tenderness/bloating. Flutamide

users must be monitored for potential

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hepatotoxicity. Because both drugs can cause feminizat ion of a male fetus,

they should be used only in women of non-childbearing potential or in

those women of childbearing potential who are using effective

contraception, preferably combination oral contraceptive pills. Cyproterone

acetate (CPA) is marketed outside the United States in conjunction with

ethinyl estradiol, either in a reversed sequential regimen of 100 mg CPA on

days 5 to 15 and 50 Âµg ethinyl estradiol on days 5 to 25, or in a low-dose

combined formulation of 2 mg CPA and 50 Âµg ethinyl estradiol on days 5

to 25. Side effects are similar to those of oral contraceptive pills.64 Topical

antiandrogens, which theoretically could also be used in men, are not

commercially available at this time.

Men with androgenetic alopecia may use a systemic 5Î±-reductase inhibitor

without the biologic concerns of emasculinization seen with systemic

antiandrogens since there is neither a decrease in testosterone levels nor


any effect on androgen-receptor binding. In men with androgenetic

alopecia, placebo- controlled studies of the type 2 5Î±-reductase inhibitor

finasteride have shown increased hair growth in ~50 percent of men at 1

year and 66 percent by 2 years.71 The placebo-treated group, by

comparison, had hair growth in 7 percent at 1 year and a progressive

decline at 2 years that continued over a 5-year follow-up.77 Sexual adverse

events (1.8 percent of those on 1 mg finasteride versus 1.3 percent of those

on placebo) were the only significant side effects and generally cleared,

either on or off treatment.71

Hair breakage

TRICHOTILLOMANIA

Trichotillomania (Greek, â€œhair pulling madnessâ € ) is a common, but

difficult to manage, cause of focal scalp hair loss. It is classified as an

impulse control disorder in which patients pull, pluck, or cut their

hair.78,79 The clinical presentation is usually quite distinctive, with a

confluence of very short sparse hairs within an otherwise normal area of

the scalp (Fig. 71-19A, Fig. 71-19B). Microscopic examination of the ends

of cut or plucked hairs generally reveals either the tapered tips of newly

regrowing anagen hairs or bluntly cut hairs. (A hair pull here is usually

negative because the telogen hairs have generally all been dislodged) The

differential diagnosis includes alopecia areata and tinea capitis, and

because patients generally deny any role in the hair loss, these usually need

to be definitively ruled out. A scalp biopsy can be diagnostic, showing the

characteristic increase in the number of catagen hairs (rarely seen in

biopsies of normal scalp), trichomalacia, and melanin within the follicular


canal secondary to traumatic hair removal and the absence or sparsity of a

perifollicular inflammatory infiltrate.80,81



FIGURE 71-19 Trichotillomania. A. Bizarre pattern of localized hair loss in

a boy. B. Extensive hair loss in a woman.

Treatment of these patients is challenging. Children with trichotillomania

may have a form of habit tic, which can be broken by mere

acknowledgment of the problem or behavior modification. Adolescents and

adults with this condition, who tend to be primarily females, are usually

particularly reluctant to accept the diagnosis and often require

psychological intervention and/or medication to help modify their

behavior.78,79 Clomipramine may be particularly effective.

TRACTION ALOPECIA

Traction alopecia is caused by inadvertent prolonged traction on the scalp

by the physical pressure of tight braids, certain hair styles (e.g., pony tail),

foam rollers, etc (Fig. 71-20). While potentially reversible, the hair loss

may be persistent if the traction is unrelenting over months to years.


FIGURE 71-20 Traction alopecia.

TINEA CAPITIS (See also Chap. 205)

Tinea capitis is a very common cause of hair breakage or loss, particularly

in children. Typically, there is either a seborrheic dermatitis presentation,

with or without erythema of the scalp (Fig. 71-21A), or a noninflammatory

â€œblack dot ring-wormâ € presentation, with broken hairs filling, but not

projecting from, follicular orifices (Fig. 71-21B). Less commonly, tinea

capitis can present as a pyoderma-like kerion.



FIGURE 71-21 Tinea capitis. A. Endothrix infection caused by

Trichophyton tonsurans presenting as seborrheic dermatitis. B. Endothrix

infection caused by T. tonsurans . Note â€œblack dotsâ € of broken,

infected hairs within the follicular canals. (Reprinted with permission from

DeVillez RL: Infections, physical, and inflammatory causes of hair and

scaly abnormalities, in Disorders of Hair Growth: Diagnosis and

Treatment, edited by EA Olsen. New York, McGraw-Hill, 1994, pp

71â€“90.)

The etiologic agent(s) of tinea capitis varies in different parts of the world.

Currently in the United States, in which the condition is far more prevalent

in African Americans and Hispanics than in Caucasians, the usual fungal

isolate is Trichophyton tonsurans.82 This is an endothrix infection and

KOH examination of affected hairs shows arthrospores and hyphae

interspersed among the keratin fibers of the hair shaft. To establish a

diagnosis, hairs should be cultured as well as examined after KOH

preparation, s ince a positive yield by KOH alone is dependent on the

amount of inflammation and may vary from 29 to 66 percent.83 Only

ectothrix fungal infections fluoresce under Wood's light.

Treatment of tinea capitis must be by the systemic route, and contacts must

be sought and treated to prevent reinfection. Asymptomatic carriers are

common. Treatment is with griseofulvin, terbinafine, or one of the newer

azoles.82,84,85 Griseofulvin, 20 to 25 mg/kg per day of the microsized

product (or 10 to 15 mg/kg of the ultramicrosized product), is given with a

fat-containing meal until the culture is negative (generally 6 to 10

weeks).82 Griseofulvin is fungistatic. Terbinafine, an allylamine, is not


significantly affected by food and is fungicidal: doses of 62.5 to 250 mg qd

for 4 weeks (62.5 mg/day for those weighing <20 kg, 125 mg/day for those

weighing 20 to 40 kg, 250 mg/day for those weighing > 40 kg) are

effective. The azoles, itraconazole at 100 mg qd, or fluconazole 6 to 8

mg/kg for 4 to 6 weeks are effective alternative treatments. Both latter

drugs inhibit the cytochrome P450 system so drugâ€“drug interactions

should be considered. Fluconazole

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bioavailability is not affected by food. Topical sporicidal agents, such as

selenium sulfide or ketoconazole, help to limit the spread of infectious

spores.

Primary or acquired localized hair shaft abnormalities

ACQUIRED LOCALIZED TRICHORRHEXIS NODOSA

Acquired localized trichorrhexis nodosa may be seen in hair that is subject

to repetitive rubbing, such as with lichen simplex chronicus or

trichotillomania. It may also present in focal areas secondary to trauma

from chemical or

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heat processing of hair. Acquired pili torti may present as a focal patch of

fragile hair. This is usually secondary to trauma or some underlying,

potentially scarring, scalp abnormality.15 Hypervitaminosis in patients

with anorexia nervosa or retinoids have also been associated with acquired

pili torti. Bubble hair is a recently recognized and very distinctive

abnormality of the hair shaft and is characterized by rows of bubbles seen


microscopically within localized areas of brittle hair.86 Exposure to

prolonged high temperatures from curling irons or hair dryers are the usual

causative factors, and the defect is completely reversible.

Unruly hair

WOOLY HAIR NEVUS

Wooly hair nevus is a nonhereditary focal condition which usually appears

within the first 2 years of life but can occur as late as adolescence.87 Fifty

percent of cases have an associated epidermal, verrucous, or pigmented

nevus, although not necessarily immediately under the affected hair. 15

There may be associated ocular abnormalities, such as persistent papillary

membrane or retinal abnormality. Spontaneous improvement in the hair

may occur with age.

ACQUIRED PROGRESSIVE KINKING

This condition has been primarily reported in postpubescent males with

androgenetic alopecia.88 It presents with gradual curling and darkening of

the frontal, temporal, auricular, and vertex hairs. Microscopically, affected

hairs show kinks and twists, with or without longitudinal grooving.

Abnormality of cycling

ALOPECIA AREATA

As noted previously, alopecia areata can (and usually does) present as focal

hair loss.

SYPHILIS

Hair loss may be one or the sole cutaneous manifestation of secondary

syphilis. This may present as a patchy â€œmoth-eatenâ € alopecia or as

generalized thinning (Fig. 71-22). A scalp biopsy may show either a

superficial and deep perivascular mixed lymphocytic /macrophage/plasma


cell infiltrate, a peribulbar perifollicular lymphocytic infiltrate mimicking

alopecia areata, or a noninflammatory telogen effluvium picture.89,90

Serologic testing should be positive, and treatment with appropriate

antibiotics will reverse the hair loss.

FIGURE 71-22 Alopecia of secondary syphilis.

Scalp conditions associated with focal hair loss

Most eczematous conditions of the scalp do not cause hair loss, the

exception being pityriasis amiantacea, severe scalp psoriasis and

malignancies such as cutaneous T cell lymphoma or histiocytosis X. In

pityriasis amiantacea, thick tenaciously adherent scale infiltrates and

surrounds the base of a group of scalp hairs91 (Fig. 71-23). The condition

may mimic psoriasis clinically, but, in contradistinction to psoriasis, the

hair in involved areas is dislodged on attempts to physically remove the

scale. Removal of the scale in this manner can lead to scarring alopecia.


The condition usually presents in children, is best treated with keratolytics,

and usually improves with age.

FIGURE 71-23 Pityriasis amiantacea. Note area of patchy alopecia after

manual removal of adherent scale.

CICATRICIAL ALOPECIA (DESTRUCTION OF THE FOLLICLE)

The term cicatricial or scarring alopecia implies the potential of

permanent destruction of the hair follicle. Clinically, there is effacement of

follicular orifices, always in a patchy or focal distribution. A biopsy is

confirmative, showing replacement of follicles with fibrotic stellae and

either fibrosis or hyalization of surrounding collagen.92,93 and 94

Although some cases of cicatricial alopecia are due to physical or

developmental causes (e.g., pressure or aplasia cutis congenita), or to the

hair follicle being secondarily involved in a destructive process (e.g.,


â€œkerionâ € fungal infection or metastatic/primary neoplasm), most

patients seeking medical attention have a primary cicatricial alopecia.

Although these conditions have a common endpoint, they have varied

clinical and histologic features and virtually no therapies able to turn the

process completely off.

There is direct evidence in the mouse, and indirect evidence in the human,

that compromising the integrity of the sebaceous gland and/or bulge is

important in the development of the scarring process in the primary

cicatricial alopecias.95 Selective destruction of the stem cell region in mice

and graft versus host disease,96 in which an inflammatory infiltrate

involves the stem cells, can lead to follicular destruction. Moreover,

alopecia areata, in which the inflammation spares the stem cell area, does

not lead to permanent hair loss. In the asebia mouse, which lacks one gene

responsible for normal sebum production, the hair follicle is destroyed

when the shaft is unable to exit the follicle properly.95 Other animals with

sebaceous gland pathology also develop cicatricial alopecia.

A new classification system based on the type of inflammatory infiltrate on

biopsy (Table 71-4) along with recommended standardization of biopsy

site, processing and pathology parameters, and cataloguing of clinical

findings,97 will help us to identify and evaluate significant differences

between these entities. The primary cicatricial alopecias are presented in

keeping with this classification system.


TABLE 71-4 Proposed Working Classification of Primary Cicatricial

Alopecia

Primary cicatricial alopecia

LUPUS ERYTHEMATOSUS (See also Chap. 171)


Chronic cutaneous lupus erythematosus may present in the scalp, usually

with erythema,

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atrophy and variable hypopigmentation and/or follicular plugging (Fig. 71-

24). Patients may have no other clinical lesions nor serologic evidence of

lupus erythematosus. Scalp biopsy is generally confirmative, showing

vacuolar degeneration of the basal cell layer, a perivascular and

periadnexal lymphoid infiltrate, increased dermal mucin and sebaceous

gland loss.92 Direct immunofluorescence studies most commonly

demonstrate granular deposits of IgG and C3 at the dermalâ€“epidermal

junction and at the junction of the dermis and follicular epithelium.

Potentially effective treatments include topical, intralesional, and systemic

steroids, antimalarials, systemic retinoids, and thalidomide.93,98


FIGURE 71-24 Lupus erythematosus.

LICHEN PLANOPILARIS

Areas of active alopecia in lichen planopilaris are clinically distinguished

by perifollicular erythema and/or a violaceous discoloration of the scalp

(Fig. 71-25). Keratotic follicular papules may be evident. Evidence of

lichen planus may be present elsewhere, and this should be sought to help

confirm the diagnosis. Histologically, there is a perifollicular lymphoid,

often bandlike, infiltrate primarily in the infundibular and isthmus portions

of the follicle, with or without the presence of adjacent colloid bodies. The

typical overlying histologic changes of lichen planus may or may not be

present; these include sawtooth rete ridges, interface dermatitis,

hypergranulosis, and Civatte bodies.99 Immunofluorescence findings

consist of globular deposits of IgM adjacent to follicular epithelium and


patchy or linear fibrogen deposits along the basement membrane zone.

Glucocorticoids are the mainstay of treatment.

FIGURE 71-25 Lichen planopilaris.

Lichen planopilaris histologically can be seen in two other disparate

conditions. Graham-Little syndrome is characterized by lichen planus-like

lesions and a follicular â€œspinesâ € /keratosis pilaris-like picture that

develop in areas of alopecia on the scalp, eyebrows, axillary, and pubic

areas.92 Frontal fibrosing alopecia is a term given to the frontotemporal

hairline recession and eyebrow loss in postmenopausal women that is

associated with perifollicular erythema, especially along the hairline.100

Scalp biopsy is indistinguishable from lichen planopilaris. Topical and

intralesional steroids, topical and systemic retinoids, and hormone

replacement therapy do not prevent the hair loss progression; oral steroids


and chloroquine have been demonstrated to slow the progression in a few

patients.

A lichenoid inflammatory infiltrate has also been seen in a progressive

inflammatory (perifollicular erythema and follicular keratosis) scarring

alopecia limited to the area of pattern hair loss.101 There appears to have

some overlap with frontal fibrosing alopecia.

PSEUDOPELADE OF BROCQ

In clinical terms, pseudopelade of Brocq implies flesh- to pink-colored,

irregularly shaped alopecia that may begin in a moth-eaten pattern with

eventual coalescence into larger patches of alopecia102 (Fig. 71-26). There

has been considerable debate as to the specificity of this diagnosis versus

an assignation of the term to describe all noninflammatory scarring

alopecias, including the end-stage of a variety of initially inflammatory

conditions. Histologically, the lesions are characterized by a perifollicular

and perivascular lymphocytic infiltrate primarily at the level of the

follicular infundibulum, loss of sebaceous epithelium, and fibrotic streams

into the subcutis without interface or follicular plugging changes.103

Elastin stains may distinguish pseudopelade (persistent elastic fibers

around the midshaft of the follicle) from lichen planopilaris and lupus

erythematosus (loss of

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elastic fibers in this location).104 Direct immunofluorescence is negative

in the majority of cases. It is unclear what treatment specifically helps.


FIGURE 71-26 Pseudopelade of Brocq.

CENTRAL CENTRIFUGAL CICATRICIAL ALOPECIA

Recently, a subset of cicatricial alopecia has been identified in African

Americans and given the name of central centrifugal cicatricial alopecia

(CCCA).97 This condition has also been called hot comb alopecia,

follicular degeneration syndrome, and central centrifugal scarring alopecia,

the latter meant to be an umbrella term for follicular degeneration

syndrome as well as other causes of central scalp hair loss.105 Affected

patients with CCCA show follicular loss primarily over the crown, with

litt le in the way of either bogginess or tautness to the scalp (Fig. 71-27).

Inflammation has been reported more commonly in affected men than in

affected women.106 Histologically, the earliest and most distinctive change

is premature desquamation of the inner root sheath with later changes


including migration of the hair shaft through the outer root sheath, a

mononuclear infiltrate primarily at the isthmus, and, finally, loss of the

follicular epithelium and replacement with fibrous tissue.106 Although

tight braiding, hot combs, and hair straightening agents are often invoked

as causative or at least contributory factors and their use discouraged in

CCCA, this has not been definitely proven. The distribution of CCCA

overlaps that of pattern hair loss but the sex distribution is tremendously

skewed toward women.

FIGURE 71-27 Central centrifugal cicatricial alopecia.

ALOPECIA MUCINOSA

Alopecia mucinosa generally presents, but not exclusively, as erythematous

plaques or flat patches without hair primarily on the scalp and face.94

Biopsy reveals prominent follicular, epithelial and sebaceous gland mucin,

and perifollicular lymphohistiocytic infiltrate without concentric lamellar

fibrosis.92,94


KERATOSIS FOLLICULARIS SPINULOSA DECALVANS

Keratosis follicularis spinulosa decalvans (KFSD) is an X-linked disorder

with the gene located at Xp22.13â€“p22.2.107 Female carriers are

frequently affected. The disorder is characterized by follicular

hyperkeratosis, scarring alopecia of the scalp, absence of eyebrows and

sometimes eyelashes, severe photophobia, and resulting corneal dystrophy.

Onset is in early childhood and the symptoms decrease with age.

Histopathologically, there is plugging of the pilosebaceous orifices with

keratinaceous debris, and superficial and deep perivascular and

periappendageal infiltrate of lymphocytes and plasma cells. Retinoids may

be useful in treatment.

FOLLICULITIS DECALVANS

Folliculitis decalvans is an inflammatory alopecia that leads to bogginess

or induration of involved parts of the scalp along with pustules, erosions,

crusts, and scale108 (Fig. 71-28). Predictably, Staphylococcus aureus is

usually cultured from these pustules, but whether this is a primary or

secondary process is unclear. Histologically, early lesions show an acute

suppurative folliculitis with neutrophils and eosinophils, later mixed with

lymphocytes and histocytes.92,93 Loss of sebaceous epithelium and

perifollicular fibrosis is common.92 Systemic antibiotics with or without

rifampin, systemic and/or topical steroids, and systemic retinoids may also

be helpful.108


FIGURE 71-28 Folliculitis decalvans.

DISSECTING FOLLICULITIS

Dissecting folliculitis or perifolliculitis capitis abscedens et suffodiens of

Hoffman is another inflammatory condition of the scalp that can lead to

scarring alopecia. African Americans are primarily affected. This condition

begins with deep inflammatory nodules, primarily over the occiput, that

progress to coalescing regions of boggy scalp (Fig. 71-29). Sinus tracts

may form and dislodge purulent material. As in folliculitis decalvans, S.

aureus is the most common bacterial isolate. Biopsy of early lesions shows

follicular plugging and suppurative follicular or perifollicular abscesses

with a mixed inflammatory infiltrate of neutrophils, lymphocytes, plasma

cells, or eosinophils.92,93 and 94 Later, foreign-body giant cells,

granulation tissue, and, finally, scarring with sinus tracts occur. Control is

difficult to attain, but systemic steroids, systemic antibiotics, dapsone, or

P.650


retinoids109 are useful therapies. Surgical incision and drainage, excision

with grafting, and/or x-ray epilation are occasionally used for refractory

cases.

FIGURE 71-29 Dissecting folliculitis .

ACNE KELOIDALIS

Acne keloidalis (nuchae) is a destructive scarring folliculitis that occurs

almost exclusively on the occipital scalp of African Americans, primarily

men (Fig. 71-30). The clinically distinctive lesions begin as follicular

pustules and papules and progress to persistent firm papules or coalesce

into hairless keloid-like plaques.110 On histopathologic examination of an

early lesion, there is follicular dilatation and a mixed peri-infundibular

infiltrate that goes into follicular rupture and foreign body granulomas, loss

of sebaceous glands, and lamellar fibroplasia. Treatment with systemic


antibiotics, topical and/or intralesional steroids, and cryosurgery is usually

helpful.

FIGURE 71-30 Acne keloidalis.

ACNE NECROTICA

The primary lesion in acne necrotica is a pruritic or painful erythematous

follicular-based papule that develops central necrosis and crusting and

heals with a varioliform scar.111 The lesions are concentrated on the nose,

forehead and anterior scalp but may spread, primarily to the trunk. The

course is chronic. Pathology is characterized by follicular dilatation, an

early mixed lymphocytic/neutrophilic infiltrate in the peri-infundibulum,

and later a lymphocytic/plasmacytic perivascular and perifollicular

infiltrate. Lymphocytic exocytosis and individual cell necrosis of

keratinocytes within the outer root sheath and surrounding epidermis go on

to confluent necrosis of the central follicle. Treatment with tetracycline is

generally helpful and cis-retinoic acid may be of value.111


EROSIVE PUSTULAR DERMATOSIS

Erosive pustular dermatosis of the scalp presents with pustules, erosions,

and crusts on the scalp of primarily older Caucasean females (Fig. 71-

31).112 On biopsy, there is a lymphoplasmacytic infiltrate Â± foreign body

giant cells and pilosebaceous atrophy. These lesions have a slow but

progressive course. Multiple organisms, both bacterial and fungal, have

been cultured but these probably represent secondary colonization; patients

do not generally respond to antibacterial or antifungal drugs. Potent topical

steroids, zinc sulfate, or isotretinoin may be helpful.

FIGURE 71-31 Pustular dermatosis of the scalp.

Secondary Cicatricial Alopecia

Cicatricial alopecia may present as a hereditary or development problem,

alone or as part of a syndrome. Examples of the latter are Conradi-

HÃ¼nermann chondrodysplasia punctata; incontinentia pigmenti;

ankyloblepharon, ectodermal defect, cleft lip or palate (AEC) syndrome;


Hallermann-Streiff syndrome; and generalized atrophic benign

epidermolysis bullosa.13

The most common congenital c icatricial alopecia is aplasia cutis congenita,

which is the congenital focal absence of epidermis with or without absence

of other layers of the skin.13 Hair follicles in the involved areas are

variably affected. The condition may present at birth as an ulceration,

crust, scar, or parchment-like membrane (Fig. 71-32). Eighty-five percent

of aplasia cutis congenita presents on the scalp, and 70 percent of affected

patients have only a single lesion. The lesions are usually small and round

but can be large and extend to the dura or meninges. Aplasia cutis

congenita may occur alone or in conjunction with various other

abnormalities. Unless the lesions of aplasia cutis congenita are very large,

no specific treatment is needed.

FIGURE 71-32 Aplasia cutis congenita. (Photograph courtesy of Neil

Prose, MD.)


EXCESS HAIR

Hirsutism refers to hair growth in women in areas of the body where hair

growth is under androgen control and in which normally only postpubescent

males have terminal hair growth. These areas include the moustache, beard,

chest, escutcheon, and inner thigh.

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Hypertrichosis specifically refers to hair density or length beyond the

accepted limits of normal for a particular age, race, or sex. The excess hair

may be generalized or localized and may consist of lanugo, vellus, or

terminal hair.

Hirsutism

Table 71-5 lists the causes of hirsutism. Most cases of hirsutism secondary

to hyperandrogenism are associated with irregular menses or amenorrhea.

There may be evidence of other cutaneous androgen-sensitive disorders

such as acne and female pattern hair loss, or cutaneous clues to a related

systemic problem such as acanthosis nigricans seen with insulin-resistant

diabetes. Virilization is uncommon and should lead one to consider an

underlying androgen-producing tumor.


TABLE 71-5 Hirsutism

For endogenous causes of hirsutism, a simple screening test of serum free

or total testosterone will often determine whether further testing is

necessary. Elevation of testosterone levels well above the upper limits of

normal indicates the necessity of screening for an ovarian or adrenal tumor.

Far more common is the mild elevation of androgens in an otherwise

healthy woman, which is most commonly secondary to either polycystic


ovarian syndrome (PCOS) or late-onset congenital adrenal hyperplasia

(CAH). PCOS is multifactorial, with a pituitary and gonadal component, as

well as hyperinsulinemia that may lead to increased production of

androgen, decreased production of estrogen, and anovulation.113,114 The

most common cause of late-onset CAH is 21-hydroxylase deficiency with

overproduction of 17-hydroxyprogesterone.64 3Î²-Hydroxylase and 11Î²-

hydroxylase deficiency may also present with late-onset hirsutism;

overproduction of 17-hydroxypregnenolone and 11-deoxycortisol,

respectively, occur with these enzyme deficiencies. The diagnosis of late-

onset CAH, while suggested by an elevated level of

dehydroepiandrosterone and testosterone, can only be established by a

cosyntropin-stimulation test showing the expected rise in the specific

steroid hormone that builds up immediately behind the enzyme blockade or

deficiency.64 Women with hyperprolactinemia may have an increase in

functional androgens through adrenal overproduction and through a

decrease in sex hormone-binding globulin (SHBG) caused by a diminution

of ovarian estrogen production; a prolactin level is diagnostic.115

The effective treatment of hirsutism depends on the cause, but the

mainstays of treatment are oral contraceptive pills, both for their direct

effect on lowering androgen production and indirect effect on lowering

androgen bioavailability by increasing SHBG, and for their contraceptive

effect when used with antiandrogens or 5Î±-reductase inhibitors.

Antiandrogens, such as spironolactone, flutamide, or cyproterone acetate

(see discussion of antiandrogens in â€œPattern Hair Loss,â € above), are

particularly useful in hirsutism as is finasteride.116 There are marginal

differences in efficacy between these agents but all generally take 6 to 12


months for sufficient miniaturization of terminal hairs to occur to be

clinically significant. Treatment of congenital adrenal hyperplasia may also

be accomplished through the use of low-dose dexamethasone.

Hyperprolactinemia may be treated directly with either medical

(bromocriptine) or surgical treatment of the hyperprolactinoma, and/or an

antiandrogen may be utilized.

Hypertrichosis

GENERALIZED HYPERTRICHOSIS: INHERITED

Congenital hypertrichosis lanuginosa presents as a confluent, generalized

overgrowth of silvery blonde to gray lanugo hair at birth or in early

infancy. It is rare (1 in 1 billion) and thought to occur as an autosomal

dominant trait with variable expressivity. In most cases, other than possibly

anomalous dental eruptions, children are otherwise healthy. The hair may

persist, increase, or decrease with age.117

There are several other congenital disorders associated with generalized

hypertrichosis, but none that are so evenly distributed as congenital

hypertrichosis lanuginosa. These are noted in Table 71-6.118 Patients with

the autosomal dominant Ambras syndrome or hypertrichosis universalis

congenita present with much longer, thicker hair, with accentuation over

the entire face, ears, and shoulders.119 Associated facial dysmorphism and

dental anomalies are common. Members of the five-generation family

described with congenital generalized hypertrichosis also have excess

terminal hair on the face and upper body, more severe in men than women

in keeping with the X-linked dominant inheritance.120 Patients with the

autosomal dominant (rarely autosomal recessive) gingival fibromatosis

frequently have hypertrichosis, mostly on the face, eyebrows, limbs, and


upper back, along with seizures and oligophrenia.118 Hypertrichosis may

be delayed until puberty although gingival fibromatosus in this s ituation

usually appears with the emergence of the primary, versus secondary, teeth.



TABLE 71-6 Causes of Generalized Hypertrichosis

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ACQUIRED GENERALIZED HYPERTRICHOSIS

There are few more ominous signs in dermatology than the onset of

generalized hypertrichosis without an obvious drug-related explanation.

Acquired hypertrichosis lanuginosa almost always signals an underlying

malignancy or is a harbinger of one to develop in the near future (Fig. 71-

33).121

FIGURE 71-33 Acquired hypertrichosis lanuginosa. (From Olsen,118 with

permission.)

There are several drugs that routinely cause generalized hypertrichosis (see

Table 71-6).118 Oral minoxidil, a piperidinopyramidine derivative that is a


potassium channel opener and antihypertensive agent when used

systemically, causes hypertrichosis in 80 percent of patients, most

prominently over the face, shoulders, and extremities. Diazoxide, a

benzothiadiazine used primarily in malignant hypertension or idiopathic

hypoglycemia of infancy, leads to lanugo-like hypertrichosis of the face,

trunk, and extremities in 1 to 20 percent of adults but in almost 100 percent

of children. Dilantin use leads to terminal hair hypertrichosis in 5 to 12

percent of patients, again first over the extremities, trunk, and face.

Cyclosporine, a cyclic undecapeptide of fungal origin and an

immunosuppressive agent, causes terminal hair hypertrichosis in 40 to 95

percent of patients, with a more diffuse distribution of excess hair, but

primarily over the upper body (Fig. 71-34).122,123

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Both diazoxide and cyclosporine are also associated with gingiva l

hyperplasia.


FIGURE 71-34 Cyclosporine-related hypertrichosis.

Certain medical illnesses are associated with widespread, although not

confluent, hypertrichosis. They are listed in Table 71-6.

Localized Hypertrichosis

Table 71-7 lists the conditions associated with localized hypertrichosis.

These are generally either inherited, developmental, or secondary to

irritation or trauma.



TABLE 71-7 Causes of Localized Hypertrichosis

Treatment of Hypertrichosis

Removal of the inciting cause should be the prime approach to treatment

and usually leads to regression of the hypertrichosis. However, in situations

where that is not possible, one must either help the patient deal

psychologically with the physical anomaly and/or use means of either

temporarily or permanently removing the hair. Depilatories, plucking,

waxing, and shaving are all means of temporarily removing hair but, with

the exception of shaving, may be associated with irritation and/or

pseudofolliculitis barbae. Potentially, electrolysis can permanently remove

unwanted hair, but this technique varies widely in effectiveness depending

on the training of the electrologist, the type of machine, the pulse

frequency, the intensity and duration applied, and the probe used.1 Two

main types of electrolysis are in general use, thermolysis (AC current) with

destruction of the hair by local heat production and â€œthe blend,â € a

combination of thermolysis and galvanic (DC current) which produces

destruction of the hair by local production of caustic lye and H2 gas.

Potential, but ultimately controllable, side effects of electrolysis are pain,

scarring, infection, and folliculitis.

Recently, several different kinds of laser have been approved for removal

of hair.1 The lasers selectively target the hair follicle, either by targeting a

chromophore that is a natural component of the follicle, such as melanin, or

one that is introduced into the follicle. The ruby (694 nm), alexandrite (755

nm), and semiconductor diode (800 nm) lasers, as well as a flash-lamp

device with filters able to deliver light of >590 nm, each target melanin in


the hair shaft and cause selective thermal injury.1 The limiting factor in

selecting melanin as the target is the concomitant absorption by epidermal

melanin with both potential epidermal injury and a diminution in energy

dispersal down the hair follicle. The Q-switched neodymium:yttrium-

aluminum-garnet (Nd:Yag) laser with a wavelength of 1064 nm does not

target melanin; instead, it targets a topically applied carbon-based material

that leads to both thermal and mechanical damage to the follicle. All of the

aforementioned lasers induce temporary hair removal. None of these

techniques has been proven to lead to complete and permanent hair

removal, although those that target melanin clearly can lead to a long-term

reduction in terminal hair density, much apparently due to miniaturizat ion,

versus destruction, of the follicles.124 A more experimental treatment is

photodynamic therapy based on a topical photosensitizer (aminolevulinic

acid), and subsequent exposure to red light, which causes selective

follicular damage by the synthesis of the potent photosensitizer,

protoporphyrin.1

CONCLUSION

The range of abnormalities in hair disorders mirrors the complexities of

hair production. The astute clinician is able to diagnose hair disorders by a

combination of clinical clues, microscopic evaluation of hairs, a biopsy of

the affected area, and confirmatory laboratory tests. Treatment efficacy

mirrors diagnostic accuracy although we are currenly woefully short of

treatment to help those patients with herediary disorders of hair follicle or

shaft production. As we come to better understand the genetic and

molecular controls on hair growth, earlier diagnosis and implementation of


effective directed treatments for the primary disorders of hair loss or

overgrowth will become possible.

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