Renal malakoplakia as a pseudotumoral lesion in a renal transplant patient: a case report.

Malakoplakia is a rare chronic inflammatory disease associated with gram-negative bacterial infections frequently caused by Escherichia coli. Malakoplakia usually affects the lower urinary tract (bladder) but there are cases described in the kidney as well as in the respiratory and digestive organs. We report on a case with renal parenchymal malakoplakia in a renal transplant patient and describe the pathological lesions of malakoplakia: histiocytic proliferation with scarce inflammatory infiltrate, histiocytes with acidophilic cytoplasm and the presence of characteristic Michaelis-Gutmann bodies. The authors in this study review the updated reports related to the entity in this uncommon localization, the association with an immunocompromised patient, the macroscopic presentation as a pseudotumoral lesion and the possible relationship with the xanthogranulomatous pyelonephritis as a form of a histopathological spectrum in patients affected with gram negative urinary tract infection.