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.
D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D006644:Histiocytes / Q000473:pathology / Q000648:ultrastructure; D006801:Humans; D002479:Inclusion Bodies / Q000473:pathology / Q000648:ultrastructure; D008287:Malacoplakia / Q000382:microbiology / Q000473:pathology*; D008875:Middle Aged; D012867:Skin / Q000473:pathology / Q000648:ultrastructure; D012874:Skin Diseases, Infectious / Q000382:microbiology / Q000473:pathology*