Table 3 Common differential diagnosis of AD [9]
From: Atopic dermatitis
| Â | Main age group affected | Frequencya | Characteristics and clinical features |
|---|---|---|---|
Other types of dermatitis | |||
 Seborrheic dermatitis | Infants | Common | Salmon-red greasy scaly lesions, often on the scalp (cradle cap) and napkin area; generally presents in the first 6 weeks of life; typically clears within weeks |
Adults | Common | Erythematous patches with yellow, white, or grayish scales in seborrheic areas, particularly the scalp, central face, and anterior chest | |
 Nummular dermatitis | Children and adults | Common | Coin-shaped scaly patches, mostly on legs and buttocks; usually no itch |
 Irritant contact dermatitis | Children and adults | Common | Acute to chronic eczematous lesions, mostly confined to the site of exposure; history of locally applied irritants is a risk factor; might coexist with AD |
 Allergic contact dermatitis | Children and adults | Common | Eczematous rash with maximum expression at sites of direct exposure but might spread; history of locally applied irritants is a risk factor; might coexist with AD |
 Lichen simplex chronicus | Adults | Uncommon | One or more localised circumscribed lichenified plaques that result from repetitive scratching or rubbing because of intense itch |
 Asteatotic eczema | Adults | Common | Scaly, fissured patches of dermatitis overlying dry skin, most often on lower legs |
Infectious skin diseases | |||
 Dermatophyte infection | Children and adults | Common | One or more demarcated scaly plaques with central clearing and slightly raised reddened edge; variable itch |
 Impetigo | Children | Common | Demarcated erythematous patches with blisters or honey-yellow crusting |
 Scabies | Children | Commonb | Itchy superficial burrows and pustules on palms and soles, between fingers, and on genitalia; might produce secondary eczematous changes |
Congenital immunodeficiencies | |||
 Hyper-IgE syndrome | Infants | Rare | Pustular and eczematous rashes within first weeks of life; staphylococcal infections of the skin, sinuses, and lungs; high serum IgE; eosinophilia |
 Wiskott-Aldrich syndrome | Infants | Very rare | Rash identical to that of AD, usually in first weeks of life in boys; microthrombocytopenia |
 Omenn syndrome | Infants | Very rare | Early-onset erythroderma, diffuse scaly rash, and chronic diarrhea |
Keratinization disorders | |||
 Ichthyosis vulgaris | Infants and adults | Uncommon | Dry skin with fine scaling, particularly on the lower abdomen and extensor areas; perifollicular skin roughening; palmar hyperlinearity; full form (i.e., 2 FLG mutations) is uncommon; often coexists with AD |
 Netherton syndrome | Infants and adults | Very rare | Eczematous lesions spread over the skin in a serpiginous linear pattern with double-edged scales; hair shaft anomalies (bamboo hair); increased IgE; eosinophilia |
Nutritional deficiency | |||
 Zinc deficiency | Children | Uncommon | Erythematous scaly patches and plaques most often around the mouth and anus; rare congenital form accompanied by diarrhea and alopecia |
Neoplastic disease | |||
 Cutaneous T-cell lymphoma | Adults | Uncommon | Erythematous pink-brown macules and plaques with a fine scale; poorly responsive to topical steroids; variable itch (in early stages) |