The histological and ultrastructural features of a case of malakoplakia affecting the testis and the epididymis of a 53-year-old man are described. Light microscopy shows a granulomatous inflammatory process, characterized by the accumulation of large mononuclear cells with abundant granular cytoplasm and PAS-positive calcific intracytoplasmic inclusions (so-called Michaelis-Gutman bodies). On E.M., such inclusions appear as concentric lamellated structures with a mineralized core. Although the pathogenesis of malakoplakia is still unclear, an abnormality of the bacteria-digesting function of tissue macrophages, leading to persistence of phagolysosomes, has been postulated. Malakoplakia of testis is a benign entity, which must be differentiated from neoplastic lesions, especially germ cell tumours, and granulomatous disease such as histoplasmosis, mycobacteriosis and idiopathic granulomatous orchitis
