Pseudoleukemia cutis: report of a case in association with molluscum contagiosum.

Histologic sections from a solitary cystic cutaneous lesion that showed atypical mononuclear cells in the dermis and within blood vessels were diagnosed by several general pathologists and dermatopathologists as leukemia cutis. The patient, who had no other cutaneous lesions, was consequently submitted to an extensive investigation for leukemia, which proved negative. Additional and deeper sections from the original block revealed that the cellular infiltrate so suspicious of leukemia cutis was secondary to rupture of a lesion of molluscum contagiosum. The correct histopathologic diagnosis, therefore, was pseudoleukemia cutis. The lessons of the case are that 1) further study of the specimen, solitary as it was and asymptomatic as the patient was, would have obviated worry and the expense and inconvenience of an extensive systemic investigation, and that 2) the diagnosis of leukemia cutis should never be made solely on the basis of histologic sections of skin, but rather after examination of blood and bone marrow.