Pigmenting pityriasis alba.

We conducted a prospective study of 20 patients with pigmenting pityriasis alba (PPA) over a period of two years. Characteristic morphology revealed a central zone of bluish hyperpigmentation surrounded by a hypopigmented, slightly scaly halo of variable width. All patients displayed lesions on the face. Concomitant extrafacial involvement was uncommon. A significant finding was an associated dermatophyte infection in 13 patients (65%). These patients all received griseofulvin 10 mg/kg/day for eight weeks, resulting in the resolution of PPA in seven within 4 to 20 weeks. These were also treated with 1% hydrocortisone. Biopsy specimens from two patients showed similar features, namely, a subacute dermatitis with variable pigment incontinence. Immunohistochemical labeling revealed a preponderance of T lymphocytes. Pigmenting pityriasis alba seems to be a variant of classic pityriasis alba showing a strong association with dermatophyte infection, especially tinea capitis. It may be related to lichenoid melanodermatitis.