Making a reliable diagnosis of adult-onset atopic dermatitis can be challenging. Many patients are also afflicted with hand eczema and thick nummular lesions that are resistant to topical medications.
Adding to the fray are adults who have forgotten they had childhood eczema in the first place.
“The entire subject is fraught with many crucial points of contrast and conflicting yet poorly documented opinions,” writes John Hanifin, M.D., in Dermatologic Clinics.
Dr. Hanifin, of Oregon Health and Science University in Portland, Ore., says there are no validated criteria for defining the category of adult-onset atopic dermatitis (AD), but the disease is assumed to be characterized by childhood onset, despite many adults having no memory of childhood eczema.
Claims of adult-onset atopic dermatitis are associated with a childhood living in a humid sunny or tropical climate; the first atopic dermatitis diagnosis made only after a change of residence to a cold dry climate or exposure to central heating; onset of hand eczema after all other features of atopic dermatitis have regressed; and recurrence of atopic dermatitis after an infection or other stressor.
Some dermatologists, however, believe that patients with one or two mild dorsal hand lesions are much more likely to have allergic contact dermatitis (ACD) than atopic dermatitis.
“Even with patch testing, the causative distinction between the AD versus ACD is often unclear because patients with AD typically have epidermal barrier defects that can predispose to contact sensitization without actual delayed hypersensitivity lesions,” Dr. Hanifin reports.
Other differential diagnosis in adult atopic dermatitis are irritant contact dermatitis (ICD), psoriasis, seborrheic dermatitis, cutaneous lymphoma and scabies.
Dr. Hanifin says biopsies may be useful to distinguish between eczema and psoriasis, but may add uncertainty due to the common and confusing “psoriasiform dermatitis” hedge.
Nonetheless, a biopsy in patients with adult atopic dermatitis will rule out possible cutaneous T-cell lymphoma.
For most adult atopic dermatitis, medications provide only partial control. Whereas topical agents are for the most part ineffective, superpotent topical corticosteroids may provide more relief.
In cases where the skin is thicker, patients can practice effective prehydration (soaks, swims or wet cloth coverings) for 20 minutes prior to using the corticosteroids.
The downside of occlusion with vinyl or nitrile gloves is that is can stimulate sweating and itching.