Table 4.
Distinguishing clinical features of most prominent differential diagnoses. [blank] indicates rare/unusual; ✓, sometimes; ✓+, often/usually; ✓++, always/nearly always/most often; Δ, variable; –, not applicable; AD, atopic dermatitis; ARCI, autosomal recessive congenital ichthyosis; CS, corticosteroids; CTCL, cutaneous T-cell lymphoma; TCS, topical corticosteroids; XLRI, X-linked recessive ichthyosis; a Concurrent disease may be observed (i.e., “overlap”).
| History | Signs/Symptoms | Distribution | Other Distinguishing/Diagnostic Features | ||||
|---|---|---|---|---|---|---|---|
| Infantile Onset | Associated with AD | Pruritus/Excoriations | Xerosis | Well Circumscribed Lesions | |||
| Atopic Dermatitis | ✓++ | – | ✓++ | ✓++ | infants: face, trunk, extensor extremities | chronic with intermittent flares | |
| children: flexors | |||||||
| adults: hands | |||||||
| all ages: spares “diaper area”/groin, axilla | |||||||
| Seborrheic Dermatitis a | ✓++ | ✓ | scalp, face, skin folds | coarse, greasy, yellow scale | |||
| Psoriasis a | ✓ | ✓ | ✓++ | extensors, scalp, “diaper area”; “Köebnerizes” | thick, silvery-white scaling | ||
| Nummular Dermatitis a | ✓ | ✓ | ✓+ | ✓++ | extremities | very TCS-responsive | |
| Irritant Contact Dermatitis | ✓ | ✓+ | ✓+ | ✓+ | ✓+ | geographic, often asymmetric | history of irritant exposure |
| Allergic Contact Dermatitis a | ✓ | ✓++ | ✓ | ✓+ | often bilaterally symmetric | history of allergen exposure | |
| Dermatographism | ✓+ | ✓++ | ✓+ | “Köebnerizes” | clinical response to mechanical stimulation | ||
| Pityriasis Alba | ✓+ | ✓+ | ✓+ | face, trunk, extremities | poorly circumscribed, hypopigmented lesions; nonpruritic | ||
| Impetigo | ✓+ | ✓ | ✓+ | face, trunk, extremities | honey-colored crust, tenderness | ||
| Secondary Syphilis | ✓+ | ✓+ | trunk, extremities | mucous membrane and palmoplantar involvement | |||
| Molluscum Dermatitis | ✓+ | ✓+ | ✓+ | ✓+ | face, trunk, extremities | frequently localized; umbilicated papules (often subtle) | |
| Eczema Herpeticum/Vaccinatum | ✓+ | ✓+ | ✓+ | ✓+ | face, AD-affected areas | “punched out” lesions | |
| Eczema Coxsackium | ✓+ | ✓+ | ✓+ | ✓+ | AD-affected areas | acute onset, fever, subsequent onychomadesis | |
| Viral Exanthem | ✓++ | ✓ | ✓ | face, trunk extremities | acute onset, associated constitutional symptoms | ||
| Tinea | ✓ | ✓ | ✓++ | scalp, face, trunk, extremities | trailing edge scale, lymphadenopathy, hair loss | ||
| Candidiasis | ✓++ | ✓ | ✓ | ✓ | skin folds, genitalia | paronychia and/or thrush | |
| Scabies | ✓+ | ✓++ | ✓ | infants: palms, soles, face, scalp adults: finger webs, wrists, periareolar, genitals |
visible burrows, palmoplantar pustules | ||
| Letterer-Siwe Disease | ✓++ | ✓ | skin fold and scalp accentuation | telangiectatic, hepatosplenomegaly | |||
| Early-Stage CTCL | ✓ | trunk, extremities | symptoms accompanied by weight loss or malaise | ||||
| Keratosis Pilaris | ✓ | ✓+ | ✓ | ✓+ | cheeks, extensor extremities | follicular keratotic papules, underlying macular erythema | |
| Ichthyosis Vulgaris | ✓+ | ✓+ | ✓ | ✓++ | spares popliteal and antecubital fossae | plate-like scale, palmoplantar hyperlinearity, non-responsive to CS | |
| XLRI (males only) | ✓++ | ✓ | ✓++ | extensor surfaces, neck, face, trunk, buttocks | grey adherent scale | ||
| ARCI | ✓++ | ✓ | ✓++ | face, trunk, extremities | “collodion baby” | ||
| Immunodeficiency Disorders | ✓++ | ✓ | Δ | Δ | variable | laboratory confirmation | |
| Nutritional Disorders | ✓ | ✓ | Δ | ✓ | variable | laboratory confirmation | |
| Acute Graft-versus-Host Disease | ✓ | ✓++ | face, trunk, extremities | oral mucous membrane/palmar involvement | |||
| Drug Eruptions | ✓ | ✓ | ✓ | face, trunk, extremities | clinico-pathological correlations | ||