holocrine secretion of sebum
Functions of sebum
1. lubricates and waterproofs the skin, and protects it
from drying
2. mildly bactericidal and fungistatic.
Free sebaceous glands may be found in the eyelid
(meibomian glands), mucous membranes (Fordyce
spots), nipple, perianal region and genitalia.
especially dihydrotestosterone, stimulate sebaceous
gland activity.
Human sebaceous glands contain 5a-reductase, 3a-
and 17a-hydroxysteroid dehydrogenase, which
convert weaker androgens to dihydrotestosterone,
which in turn binds to specific receptors in
sebaceous glands, increasing sebum secretion.
The sebaceous glands react to maternal androgens
for a short time after birth
disorder of the pilosebaceous apparatus
characterized by comedones, papules, pustules,
cysts and scars.
all teenagers have some acne (acne vulgaris)
affects the sexes equally
ages of 12 and 14 years, tending to be earlier in
females.
Sebum
Sebum excretion is increased. However, this alone need not cause acne
Hormonal
Androgens (from the testes, ovaries, adrenals and sebaceous glands themselves) are
the main stimulants of sebum excretion,
Poral occlusion
Both genetic and environmental factors (e.g. some cosmetics) cause the epithelium to
overgrow the follicular surface.
Follicles then retain sebum that has an increased concentration of bacteria and free
fatty acids
Rupture of these follicles is associated with intense inflammation and tissue damage
Bacterial Propionibacterium acnes
normal skin commensal, plays a pathogenic part
Genetic
The condition is familial in about half of those with acne
1. Infantile acne
follow transplacental stimulation of a child’s sebaceous glands by maternal androgens.
2. Mechanical
Excessive scrubbing, picking, or the rubbing of chin straps or a fiddle
3. Acne associated with virilization
4. Acne accompanying the polycystic ovarian Syndrome
5. Drug-induced
Corticosteroids, androgenic and anabolic, steroids, gonadotrophins, oral contraceptives, lithium, iodides, bromides, antituberculosis and anticonvulsant therapy can all cause an acneiform rash.
6. Tropical, Heat and humidity
7. Acne due to cosmetics
Mostly in face, shoulders, upper chest and back.
Seborrhoea is often present
Open comedones (blackheads) because of the plugging by keratin and sebum of the pilosebaceous orifice
Closed comedones (whiteheads), caused by overgrowth of the follicle openings by surrounding epithelium
Inflammatory papules, nodules and cysts
Depressed or hypertrophic scarring
post-inflammatory hyperpigmentation
Psychological depression is common
Acne Conglobate
is severe form of acne
abscesses or cysts with intercommunicating sinuses that contain thick serosanguinous fluid or pus
On resolution, it leaves deeply pitted or hypertrophic scars, sometimes joined by keloidal bridges
Infantile Acne
present at or appears soon after birth and may last up to 3 years
Fulminans Acne
conglobate acne is accompanied by fever, joint pains and a high erythrocyte sedimentation rate (ESR)
Excoriated Acne
Late onset Acne
Women, limited to the chin, Nodular and cystic lesions predominate
It is stubborn
Tropical Acne
Drug-induced Acne
Hormonal induced Acne
Acne vulgaris clears by the age of 23–25 years in
90% of patients
5% of women and 1% of men still need treatment in
their thirties or even forties.
No need usually
Cultures are occasionally needed to exclude a
pyogenic infection, an anaerobic infection or Gram-
negative folliculitis
exclude an androgen-secreting tumour of the
adrenals, ovaries or testes, and to rule out
congenital adrenal hyperplasia caused by 21-
hydroxylase deficiency, polycystic ovarian syndrome
1. General measures
regular encouragement worthwhile
underlying cause should be removed or treated.
2. Local treatment
3. Systemic treatment
Antibiotics
Hormonal
Regular gentle cleansing with soap and water to remove surface sebum.
Benzoyl peroxide
Is an antibacterial agent
most effective for inflammatory lesions not affected by propionibacterial antibiotic resistance
start with a 2.5% or 5% preparation, moving up to 10% if necessary.
Retinoids.
normalize follicular keratinization
down-regulate TLR2 expression
reduce sebum production
effective against comedones
Side effects
skin irritation and photosensitivity
applied overnight on alternate nights
stop temporarily if irritation
worth increasing the strength of tretinoin after 6 weeks if it has been well tolerated
Contraindication
Concomitant eczema and Pregnant women
Azelaic acid bactericidal for P. acne Have an anti-inflammatory effect inhibits the formation of comedones It should be applied twice daily, but not used for more than 6
months at a timeTopical antibiotics topical clindamycin, erythromycin and sulfacetamide antibacterial resistance of P. acnes is a most erythromycin-
resistant strains being cross-resistant to clindamycin Combining antibiotics with benzoyl peroxide reduces P. acnes
numbers and the likelihood of resistant strains Emerging The addition of zinc acetate complex to erythromycin enhances
the antibiotic’s anti-inflammatory effect Cosmetic camouflage
Oxytetracycline and tetracycline.
starting dosage for an adult is 500 mg twice daily, but up to 1.5 g/day may be needed in resistant cases.
Used not less than 3 months and may be needed for 1–2 years, or even longer.
It should be taken on an empty stomach, 1 h before meals or 4 h after food, as the absorption of these tetracyclines is decreased by milk, antacids and calcium, iron and magnesium salts.
maintenance dosage being 250–500 mg/ day.
serious side-effects are rare, although candidalvulvovaginitis may force a change to a narrower spectrum antibiotic such as erythromycin.
Minocycline
50 mg twice daily or 100 mg once or twice daily is now preferred by many dermatologists
Absorption is not significantly affected by food or drink.
Minocycline is much more lipophilic than oxytetracycline and so probably concentrates better in the sebaceous glands.
can cause abnormalities of liver function and a lupus-like syndrome.
Rarely, the long-term administration of minocycline causes a greyishpigmentation, like a bruise, especially on the faces of those with actinic damage and over the shins.
Doxycycline
100 mg once or twice daily is a cheaper alternative to minocycline
more frequently associated with phototoxic skin reactions.
Contraindications
Tetracyclines should not be taken in pregnancy or by children under 12 years as they are deposited in growing bone and developing teeth, causing stained teeth and dental hypoplasia.
Erythromycin Is the next antibiotic of choice is preferable to tetracyclines in women who might become
pregnant. Its major drawbacks are nausea and the widespread
development of resistant Proprionibacteria, which leads to therapeutic failure.
Trimethoprim with or without sulfamethoxazole by some as a third-line antibiotic for acne, when a
tetracycline and erythromycin have not helped. White blood cell counts should be monitored.
Ampicillin is another alternative.
Isotretinoin
is an oral retinoid
inhibits sebum excretion, the growth of P. acnes and acute inflammatory processes.
reserved for severe nodulocystic acne, unresponsive to the measures outlined above.
It is routinely given for 4–6 months only, in a dosage of 0.5–1 mg/kg body weight/day
A full blood count, liver function tests and fasting lipid levels should be checked before the start of the course, and then 1 and 4 months after starting the drug.
Isotretinoin is highly teratogenic
Effective contraception must be taken for 1 month before, throughout and for 1 month after treatment.
Tests for pregnancy are carried out monthly while the drug is being taken only a single month’s supply of the drug should be prescribed at a time
Treatment should start on day 3 of the patient’s next menstrual cycle following a negative pregnancy test.
Other side-effects of isotretinoin include:
1. Depression rarely lead to suicide
2. a dry skin, dry and inflamed lips and eyes, nosebleeds
3. facial erythema, muscle aches
4. hyperlipidaemia and hair loss
these are reversible and often tolerable, especially if the acne is doing well.
5. Rarer and potentially more serious side-effects include changes in night-time vision and hearing loss
Rosacea affects the face of adults, usually women.
peak incidence is in the thirties and forties, it can also be seen in the young or old.
It may coexist with acne but is distinct from it.
The cause is still unknown.
Rosacea is often seen in those who flush easily in response to warmth, spicy food, alcohol or embarrassment. No pharmacological defect has been found that explains these flushing attacks.
Psychological abnormalities, including neuroticism and depression, are more often secondary to the skin condition than their cause.
Sebum excretion rate and skin microbiology are normal
The cheeks, nose, centre of forehead and chin are most commonly affected
the periorbital and perioral areas are spared
Intermittent flushing is followed by a fixed erythemaand telangiectases.
Discrete domed inflamed papules, papulopustulesand, rarely, plaques or nodules develop.
no comedones or seborrhoea.
It is usually symmetrical.
Its course is prolonged, with exacerbations and remissions.
Acne
Rosacea differs from it by:
1. its background of erythema and telangiectases
2. absence of comedones
3. distribution of the lesions is central face but not the trunk.
4. usually appears after adolescence.
Sun-damaged skin with or without acne cosmeticacauses most diagnostic difficulty
Remember, rosacea affects primarily the central, less mobile parts of the face, whereas sun damage and acne cosmetica are more generalized over the face
The flushing of rosacea can be confused with:
1. menopausal symptoms
2. carcinoid syndrome
3. Superior vena caval obstruction
Seborrhoeic eczema
perioral dermatitis
systemic lupus erythematosus
photodermatitis
they do not show the papulopustules of rosacea
Rosacea and topical steroids go badly togetherPapulopustular rosaceaSystemic tetracyclines as for acne are the traditional treatment and are
usually effective. Erythromycin is the antibiotic of second choice. Courses should last for at least 10 weeks and, after gaining
control with 500–1000 mg/day, the dosage can be cut to 250 mg/day
The condition recurs in about half of the patients within 2 years, but repeated antibiotic courses, rather than prolonged maintenance ones, are generally recommended
Rarely, systemic metronidazole or isotretinoin is needed for stubborn rosacea
Topical
Topical 0.75% metronidazole gel, 15% azelaic acid and sulfacetamide/sulphur lotions applied once or twice daily
are nearly as effective as oral tetracycline and often prolong remission
Sunscreens help if sun exposure is an aggravating factor
changes in diet or drinking habits are seldom of value