A 12-year-old boy with a history of atopy complained of pruritus and severe dryness of the hands (A). Over-the-counter moisturizers failed to resolve the condition. The patient did not wash his hands frequently and had no hobbies that exposed him to environmental irritants or allergens.
Dr Ahmad Hakemi of Mt Pleasant, Mich, noted dull erythema and deep linear grooves perpendicular to the thenar eminences on the boy's hands; no scales, crusts, or vesicles were evident. Further examination revealed areas of hypopigmentation and hyperpigmentation on the chest wall (B).
This clinical presentation is typical of atopic dermatitis, a disorder that occurs most often in infants and children. Hand dermatitis affects more than half of these patients and is frequently the only manifestation. Exacerbations and flares are very common.
Atopic dermatitis is thought to be caused by environmental factors that trigger the disease in genetically susceptible persons; it is not caused by allergens. However, consider irritant and allergic contact dermatitis in the differential. A thorough history is the most elucidating diagnostic tool and often reveals a family or personal history of atopic disorders, such as asthma or hay fever.
The major diagnostic features are:
- Severe pruritus, which can provoke an "itch, scratch, itch" cycle.
- An age-dependent distribution and morphology, which involves extensor surfaces of the extremities, face, scalp, and trunk in infants; flexural skin and neck in children; and flexural lichenification and hands and feet in adolescents and adults.
- Chronicity and recurrence of symptoms.
- A family history of asthma, allergic rhinitis, and atopic dermatitis.
Minor diagnostic features are numerous and include cheilitis, cataracts, food intolerances, elevated IgE levels, keratosis pilaris, orbital darkening, infraorbital fold, hand dermatitis, wool intolerance, hyperlinear palms, and xerosis. Three or more features from each category establish the diagnosis; the absence of pruritus makes atopic dermatitis unlikely.
Postinflammatory hypopigmented or hyperpigmented areas represent sites of previous eczematous eruptions; they are clues to past episodes of atopic dermatitis in this patient. Postinflammatory pigmentary changes occur in many chronic inflammatory disorders in which scratching or rubbing is prevalent. Typically, hyperpigmented areas are muddy brown.