Diagnosis: Chronic atopic dermatitis
Although the patient was told she had psoriasis by previous doctors, we diagnosed her condition as atopic dermatitis based on its clinical appearance. There is no single test that can establish a diagnosis of atopic dermatitis. While serum total IgE levels are often elevated, testing is not currently recommended.
The United Kingdom working group on atopic dermatitis published diagnostic criteria based on clinical history and physical exam that include pruritic skin in addition to the presence of 3 or more of the following: skin crease involvement, chronically dry skin, symptom onset before 2 years of age, and visible evidence of dermatitis involving flexural surfaces.1 Our patient fulfilled all but one condition, as she wasn’t sure if her symptoms began before age 2.
Atopic dermatitis is a chronic and inflammatory cutaneous disease that affects approximately 10% to 12% of children and less than 1% of adults in the United States.2 Approximately 90% of cases present before the age of 5 and the literature demonstrates a slight female predominance.3,4
Disease severity is classified as mild, moderate, or severe.5 Mild disease is characterized by dry skin and minimal itching with little impairment of the patient’s physical and psychological wellbeing. Moderate disease includes frequent pruritus and erythema with or without secondary skin changes and a moderate impact on physical and mental health. In severe disease, extensive secondary skin changes exist and the patient’s daily activities, sleep, and mental health may be severely impaired.
Etiology is multifactorial. Causes of atopic dermatitis include abnormalities in the epidermal stratum corneum and tight junctions, a heightened type-2 helper T-cell response to environmental antigens, innate immunity defects, and altered microbial skin flora.6,7
Genetic influences appear to play a substantial role in disease development. Approximately 70% of patients have a positive family history of an atopic disease such as eczema, asthma, or allergic rhinitis.8 Genetic defects are believed to be related to defective proteins and lipids in the epidermis that lead to disruption of the epidermal barrier and subsequent cutaneous inflammation.6,7
Clinical presentation: Lesion distribution varies with age
Intense pruritus and dry scaly skin occur in both children and adults, although the distribution of lesions may vary with age. Children typically exhibit erythematous patches with papules and crusting on the face, scalp, extremities, or trunk. In adults, lesions are primarily located on the hands and feet, but may also present on the face, wrists, forearms, and flexural areas.3
Adults also frequently present with secondary skin changes such as thickened skin, pigmentation changes, lichenification, and excoriated papules due to chronic rubbing or scratching.3 Our patient presented with significant lichenification and hyperpigmentation of the skin that was most prominent on the wrists and forearms.
Additional clinical features consistent with atopic dermatitis include a personal history of allergic conditions and a disease course characterized by exacerbations and remissions. Exacerbations may be caused by heat exposure, dry climates, anxiety, rapid temperature variations, contact with certain chemical substances, or microbial infections.8