Dermatitis: Itchy Red Rashes Jerry Tan MD FRCP University of W estern Ontario W

Objectives Describe the cutaneous features of dermatitis Differentiate acute from chronic dermatitis Contrast irritant versus allergic contact dermatitis Describe the presentation of atopic dermatitis at different ages Indicate cutaneous findings that are unique for each type of dermatitis

Dermatitis (syn. eczema) Skin inflammation characterized by: itchy, scaly, patches of ill-defined erythema Common reaction pattern of various pathogenic pathways: Epidermal barrier disruption Type IV immune injury Combinations of the above

Acute dermatitis erythema and edema papules, vesicles, and sometimes bullae accompanied by exudation and crusting

Chronic dermatitis less erythema and edema presence of lichenification, scaling, and fissuring

Contact Dermatitis = dermatitis precipitated by an exogenous agent 2 types: allergic (hypersensitivity) or irritant (direct noxious effect on skin)

Irritant contact dermatitis More common than allergic contact dermatitis Results from chronic exposure to irritants that progressively disrupt the epidermal barrier Most common irritants are: Water Abrasives Chemicals, e.g. acids and alkalis Solvents and detergents

Eg. Irritant contact hand dermatitis

Allergic contact dermatitis Due to type IV immune response by specific allergen requires induction and elicitation phase (lag time to reaction) Common allergens eliciting contact dermatitis: nickel (affects 10% of women and 1% of men), perfumes, hair dyes, rubber latex Suspect if dermatitis shows geometric patterns

Nickel Allergy - belt buckle

Nickel Allergy - bracelet

Hair dye allergy

Latex allergy - goggles

Adhesive allergy - bandage

Allergy to leather sandal straps

Management Primary objective: Identify offending allergen or irritant Flare diaries; allergic contact patch testing Avoidance of allergen(s) / irritants. Treatment: Gentle cleansers Barrier creams Topical anti-inflammatory medications

Atopic Dermatitis = chronic pruritic inflammatory dermatosis associated with personal or family history of asthma, allergic rhinitis, conjunctivitis or atopic eczema.

Atopy defines an inherited tendency, present in 15-25% of the population, to develop one or more of: asthma, allergic rhinitis/conjuncitivitis, atopic eczema Cause of atopic dermatitis: defective epidermal differentiation (filaggrin mutations) and resultant impaired barrier function of the skin

Br J Derm 2007, 157: 441

Infantile atopic dermatitis Infants develop an itchy vesicular eczema on cheeks and hands often with secondary infection.

scaling erythema fissures

Childhood atopic dermatitis Children develop antecubital and popliteal fossae, neck, wrists, and ankles. Lichenification, excoriations, and dry skin are common as well as post-inflammatory hyperpigmentation.

Flexural involvement xerosis excoriations Erythematous patches, fissures hyperpigmentation

Lichenification Accentuation of normal skin markings

Adult atopic dermatitis In adults most common manifestation: hand dermatitis. chronic severe form of generalized and lichenified atopic eczema.

Hand dermatitis

Widespread chronic atopic dermatitis

Complications of atopic dermatitis Infection: Bacterial infection: impetigo Viral infection eczema herpeticum (HSV) widespread mollusca Cataracts Growth retardation

Impetiginised dermatitis Golden yellow crust

Impetiginised dermatitis Fragile bullae with crust and erosions = bullous impetigo

Eczema Herpeticum Extensive facial erosions More tender than typical eczema

Mollusca Contagiosa Dome-shaped 1-2mm firm papules

Management Education Avoidance of irritants sweat, wool, pet dander Mild cleansers, frequent moisturisation Prescribe the least potent topical anti-inflammatory (steroid, TIMs) that is effective. Antibiotics (topical or oral) for infected eczema. +/- oral antihistamines for pruritus

Topical Steroid Classification Potency Products Hydrocortisone acetate 1% Comments Facial and intertriginous Low Moderate Strong Ultra Desonide Betamethasone valerate Triamcinolone acetonide Mometasone Amcinonide Betamethasone dipropionate Clobetasol, Halobetasol regions Elidel* equivalent Protopic* 0.1% equivalent Limit use to max 1 wk/ mth Reassess frequently *Non-steroidal antiinflammatory medications

Seborrheic dermatitis chronic, scaly inflammatory eruption usually affecting scalp and face Can also affect chest, and flexures (axillae, groin, and infra-mammary areas) due to overgrowth of the commensal yeast Pityrosporum ovale.

Seborrheic dermatitis Persistent erythematous patches with greasy scales Characteristic distribution: sides of nose, glabella, perioral region, scalp, eyebrows, ears; chest.

Seborrheic dermatitis

Truncal seborrheic dermatitis

Management Scalp: medicated shampoo (e.g. containing coal tar, selenium sulphide or ketoconazole) Face, trunk, flexures: imidazole or antimicrobial, often combined with low potency topical steroid eg HC 1% in Canesten Cream bid

Nummular Eczema Distinctive eczema with itchy coin-shaped macules/patches typically affects limbs of middle-aged or elderly Management: emollient, topical steroid

Nummular Eczema

Venous (Stasis) Eczema affects sites of stasis edema (lower legs) most patients are middle-aged or elderly Complications: ulcers, infections Management: Treatment of edema Support stockings, leg elevation, diuretics Skin treatment: emollient +/- steroid ointment

Stasis eczema

Xerotic dermatitis Diffuse background skin dryness with associated dermatitis typically affects limbs of the elderly. Aggravated by: harsh cleansers, dry winter conditions, hypothyroidism, use of diuretics Treat with emollients 1 st ; +/- mild steroid ointments

Xerotic dermatitis

What unique features are associated with different types of dermatitis?

Distinctive morphological features of different forms of dermatitis typeFeatures of dermatitisOther skin findings atopicSymmetry, changes with agexerosis seborrheicGreasy scale, face and scalp affectedoiliness nummular stasis xerotic Coin-shaped or discoid macules and patches Affects lower legs, ankles Mild, widespread; typically fall & winter xerosis Edema, hyperpigmentation xerosis allergic contact sites of contact, may have geometric patterns irritant contacttypically affects hands, faceXerosis, fissuring

Summary Describe the cutaneous features of dermatitis Differentiate acute from chronic dermatitis Contrast irritant versus allergic contact dermatitis Describe the presentation of atopic dermatitis at different ages Indicate cutaneous findings that are unique for each type of dermatitis

Acknowledgements References: Shear, Knowles and Shapiro Cutaneous Drug Reactions, Web MD Scientific American, Feb Lebwohl, M: Cutaneous Manifestations of Systemic Diseases, WebMD Scientific American Medicine, June 2003 update. Gawkrodger DJ. Dermatology an illustrated color text. Churchill Livingstone 2001 Illustrations: Dermatology Image Atlas: