Renal and prostatic malakoplakia associated with submassive hepatic necrosis. A case report with immunocytochemical, ultrastructural and X-ray analytical observations.

An autopsy case of malakoplakia involving the kidney and prostate was reported. The case was a 58-year-old Japanese male with submassive hepatic necrosis of three and half months' duration. He received 20 to 40 mg of prednisolone daily during the course of the disease (total 2,700 mg). Malakoplakic lesions were incidentally found in the right renal parenchyma and prostate at autopsy. The lesions were characterized microscopically by an accumulation of macrophages with PAS-positive intracytoplasmic granules and with intracytoplasmic inclusions of owl's eye appearance called Michaelis-Gutmann bodies and, electronmicroscopically, by numerous phagolysosomes with varying numbers of bacteria. Immunocytochemical stain revealed that the bodies were positive for lysozyme, indicating that the Michaelis-Gutmann bodies are of lysosomal origin. No calcium, phosphorous, and iron were demonstrated in them by X-ray microanalysis, suggesting that they are of immature form in which a mineralization does not take place as yet. Malakoplakia has not been previously described in association with submassive hepatic necrosis. Administration of a large amount of steroid for the treatment of submassive hepatic necrosis was suspected to be implicated in the development of the malakoplakia in the present case.