In 1954, at the 20th seminar of the American Society of Clinical Pathologists, Helwig,1 in discussing Darier's disease, described a lesion which he tentatively called isolated Darier's disease. Usually single and on the face, this lesion clinically is commonly misinterpreted as basal-cell carcinoma and less frequently, as squamous-cell carcinoma. Pathologically, the diagnosis in many instances is confused with sweat-gland tumor of some type or with squamous-cell carcinoma. Allen2 in the same year described a lesion occurring principally as an isolated focus on the scalp, histologically indistinguishable from Darier's disease except for its tendency to be two or three times larger and noticeably more irregular in pattern than the individual papule of Darier's disease. He referred to this lesion as isolated or solitary Darier's disease and noted that it was not a precursor of the disseminated disorder. In a survey of the literature,