Functional analyses of the superficial stratum corneum in atopic xerosis.

Dermatologists universally recognize that the unaffected skin of patients with atopic dermatitis tends to be dry and slightly scaly. To characterize the functional properties of the superficial stratum corneum in atopic xerosis, we studied the forearms of 28 patients with atopic dermatitis, aged 14 to 30 years, and 18 age-matched controls, with the use of mainly noninvasive methods. Patients with atopic xerosis showed markedly higher transepidermal water loss and markedly lower skin surface hydration levels than did the controls. The corneocytes in atopic xerosis tended to desquamate in clumps of cell aggregates instead of as individual cells. They contained a substantially lower amount of water-soluble amino acids, which play a role in the water-retaining capacity of stratum corneum, than did those of controls. Although the number of stratum corneum cell layers in atopic xerosis (21 +/- 4) was substantially larger than that in controls (15 +/- 1), its turnover time (7 +/- 2 days) was appreciably shorter than that for controls (14 +/- 2 days). Like those noted in the skin with increased epidermal proliferation, the size of superficial corneocytes in patients with atopic xerosis was substantially smaller than in controls. Histopathologic examination revealed acanthotic epidermis, mild perivascular mononuclear cell infiltrate, and pigment incontinence. Atopic xerosis, the dry skin of patients with atopic dermatitis, shows various stratum corneum functional impairments, probably reflecting increased epidermal proliferation due to a low-level ongoing dermatitis.