Background: Widespread hypopigmented macules are rarely seen in heavily pigmented patients with Darier's disease. Previous hypotheses concerning the cause of decreased pigmentation suggest it is a postinflammatory phenomenon or that the hypomelanosis is evidence of subclinical acantholysis.
Patients: This report presents 2 patients: a new case of disseminated guttate leukoderma in a black patient with Darier's disease and the first such case in a patient with transient acantholytic dermatosis (Grover's disease). Direct immunofluorescence and electron-microscopic studies were carried out on lesional biopsies.
Observations: Numerous small hypopigmented macules were observed in two black patients followed for acantholytic disorders. Three biopsies of the hypopigmented macules revealed acantholysis, while one showed only decreased melanin. Direct immunofluorescence studies were negative. Electron-microscopic studies of the leukodermic macules showed sparse melanocytes and melanosomes that were mostly pigmented stage IV melanosomes.
Conclusions: Disseminated guttate leukoderma can occur in transient acantholytic dermatosis, as well as in Darier's disease. It is readily apparent on darkly pigmented skin because of contrast. The etiology of this phenomenon is still unknown.