[815] Genitourinary Malakoplakia: Clinicopathologic Features and Ultrastructural Findings of 15 Cases

Athanase Billis, Luciana Meirelles, Leandro LLL Freitas, Arthur A Tavares, Flavia F Carvalho, Joao PU Fontenele, Luiz GF Cortes. School of Medicine, University of Campinas (Unicamp), Campinas, SP, Brazil

Background: Malakoplakia is an uncommon disease that affects many body tissues but most frequently involves the urinary tract, followed in order by the genital tract, gastrointestinal tract and retroperitoneum. Microscopically, is characterized by presence of large histiocytes (von Hansemann cells) admixed with intracellular and extracellular "target-like" Michaelis-Gutmann bodies. Electron microscopy has shown the origin of the bodies in phagolysosomes and the various stages of development. We describe the clinicopathologic features of 15 cases and the ultrastructural findings.
Design: The study comprised 3 cases from the kidney one in a transplant (2 females and 1 male); 3 cases from urinary bladder one associated with urothelial carcinoma (all female patients); 5 cases from the prostate one in a patient with kidney transplant; and, 4 cases from the testis. In the microscopic study we evaluated the frequency of von Hansemann cells, Michaelis-Gutmann bodies, granulomatous reaction, lymphocytes, plasmocytes, neutrophils, eosinophils, and fibrosis. The electron microscopy study was based on 3 cases fixed in Karnovsky.
Results: In none of the cases the diagnosis was suspected previously to the biopsy or surgical resection. Michaelis-Gutmann bodies were scant in 1 case from the testis, and 3 cases from the prostate showing granulomatous reaction; were in moderate number in 1 case from the testis and 1 from the kidney showing predominantly neutrophilic (exsudative) inflammation; and, very numerous in cases showing exclusively histiocytes (von Hansemann cells). Michaelis-Gutmann bodies showed strong positivity for PAS and von Kossa, however less consistently and with less intensity some bodies also stained with Perls, Grocott, Ziehl-Neelsen or mucicarmin. In the electron microscopy study we documented the origin of the Michaelis-Gutmann bodies in the phagolysosomes, the various stages of development, formation of membranous whorls, and presence of bacilli.
Conclusions: The frequency of Michaelis-Gutmann bodies is associated with the type of inflammation: when exclusively histiocytic (von Hansemann cells) they are very numerous and in granulomatous reactions scant. In the latter, the proper identification of the Hansemann cells and the targetoid Michaelis-Gutmann bodies using PAS and von Kossa stains is important for the diagnosis considering that other stains, albeit less consistently and with less intensity may also stain the bodies. The 2 transplant associated cases favor an immunossupression effect in the possible defect of histiocytes to gram-negative coliform bacteria.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 178, Wednesday Afternoon


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