Cutaneous malakoplakia*

A case of cutaneous malakoplakia is reported. The patient is a 53-year-old white woman on immunosuppressive therapy 6 years after renal transplantation for end-stage nephrosclerosis. She developed yellow-pink papular lesions in her natal cleft which, on histopathologic examination, showed typical features of malakoplakia, namely, a diffuse dermal infiltrate of histiocytes (von Hansemann cells) which contained calcified Michaelis-Gutmann bodies with a concentric ring appearance. Gram-negative bacteria were also identified in some of the histiocytes. The Michaelis-Gutmann bodies stained positively with the PAS-diastase, mucicarmine, and Grocott stains and thus resembled fungal spores from which they must be differentiated. Electron microscopy showed that the Michaelis-Gutmann bodies developed within phagolysosomes of the histiocytes. Malakoplakia appears to be caused by an acquired defect in the intracellular digestion of phagocytized bacteria.