1 Exogenous eczema Pranee Svetvilas, MD. Somdech phra Debaratana Medical Centre, Division of Dermatology Ramathibodi Hospital, Mahidol University Eczema Endogenous Exogenous Exogenous eczema or Contact dermatitis The inflammation of the skin induced by external agents Outlines • Irritant contact dermatitis • Allergic contact dermatitis • Photo contact dermatitis Contact dermatitis Irritant contact dermatitis (80%) • Direct damage of epidermal cells to various substances • Can occurred to anyone Allergic contact dermatitis (20%) • Delayed type IV hypersensitivity to external substances (allergens) • Only occurs in susceptible individuals who have been sensitized ACD and ICD may co‐exist in the same patient ICD ACD
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Exogenous eczema
Pranee Svetvilas, MD. Somdech phra Debaratana Medical Centre, Division of Dermatology
Ramathibodi Hospital, Mahidol University
Eczema
Endogenous Exogenous
Exogenous eczema or Contact dermatitis
The inflammation of the skin induced by external agents
Outlines
• Irritant contact dermatitis
• Allergic contact dermatitis
• Photo contact dermatitis
Contact dermatitis
Irritant contact dermatitis (80%) • Direct damage of epidermal cells to various substances
• Can occurred to anyone
Allergic contact dermatitis (20%) • Delayed type IV hypersensitivity to external substances (allergens)
• Only occurs in susceptible individuals who have been sensitized
ACD and ICD may co‐exist in the same patient
ICD ACD
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Irritant contact dermatitis
ICD
Introduction
• Nonspecific, nonallergic response of the skin • Direct damage to the stratum corneum by chemicals or physical agents
• Occurs faster than the skin is able to repair itself
• Can be acute or chronic • Anyone can develop ICD • Well‐demarcated, typically confined to the area of contact with the irritant
• Most common cause of hand eczema
Mechanisms of ICD:
• Disruption of epidermal barrier
• Damage keratinocyte cell membranes
• Cytotoxic effect on keratinocytes
• Cytokine released from keratinocytes
• Activation of innate immunity
Clin Rev Allergy Immunol. 2019 Feb;56(1):99–109.
The irritants
• Chemical agents • Alkaline and acid solutions, organic solvents, tensides, croton oil
• Physical agents • UV radiation, x‐rays, other ionizing radiation, laser rays, heat, cold and mechanical factors
• Food stuffs • Asparagus, mustard, fruit juices
• Plants • Agave, anemones, many others
• Chemical warfare agents
Acta Clin Croat. 2018 Dec;57(4):713‐20.
Common irritants
Detergents Surfactants
Disinfectants, antiseptics
Cosmetics
Dusts Water and
Wet work
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Water and wet work
Contact Dermatitis. 2011 Jul;65(1):3‐12.
The criteria for wet work are loosely defined, and include:
(1) Hands regularly in a wet environment for > 2 h per day
(2) Frequent hand washing (> 20 times/day)
(3) Use of hand disinfectants 20 times in a working day
(4) Use of protective gloves for > 2 h per day or change of gloves > 20 times/day
High risk occupations of ICD
• Medical personnel
• Hairdressers • Metalworkers
• Food worker • Construction and cement workers
J Am Acad Dermatol. 2020 Dec;83(6):1730‐7
Predisposing Factors‐ ICD
The Host
• Age: elderly patients, children
• Sex: women
• Body region: face, dorsal aspect of hands, and finger webs
• Atopy
The Irritant
• The nature of the irritant
• Amount of exposure
• Concentration
• Duration
• Repetition
The Environment
• Temperature
• Airflow
• Humidity
• Occlusion
Atopic dermatitis
• Filaggrin mutations
• Early‐onset dermatitis
• Greater reactivity to the irritant
• Flexural areas develop frictional irritant dermatitis
• Leads to allergic contact dermatitis
Lancet. 2016;387(10023):1109‐22.
Clinical features
• Acute ICD • Contact with a strong acid or alkali
• Mimics a chemical burn • Erythema, blisters, pustules, hemorrhage, crusts, scales, erosions and ulcers
• Pruritus or pain • Sharply bordered in the areas of contact
• Chronic ICD • Most common type • Repetitive exposure to a weak or marginal irritant over years
• Poorly defined erythematous scaly patches, dryness of skin, lichenification and desquamation
Acta Clin Croat. 2018 Dec;57(4):713‐20.
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Flexural accentuation
• Important sign of irritant dermatitis
• Common areas for irritant dermatitis are folds • Eyelid, neck
• Antecubital fossae, volar wrist
• Finger webs and creases
• Intertriginous folds
Diaper rash • Common example of irritant dermatitis
• Occur with wet‐to‐dry cycles, irritation from stool
• Decreased with the use of disposable diapers • Superabsorbent
• Prevent hyperhydration of the skin
Pediatr Dermatol. 2018 Mar;35 Suppl 1:s10‐s18.
Pustular and Acneiform Irritant Contact Dermatitis
• Workers in the mechanical industry due to contact with cutting or grinding oils
Wolff, K., Goldsmith, L., Katz, S., Gilchrest, B., Paller, AS.,& Leffell, D. (2019). Fitzpatrick's Dermatology in General Medicine, 8th Ed. New York: McGraw-Hill.