title: Malignant interstitial cell tumor of the testis.
abstract: The light microscopic and ultrastructural characteristics of a hormonally active Leydig cell tumor are described. Evidence is adduced that strongly suggests that the Leydig cell tumor was malignant and that functioning metastases were present.
mesh_terms: D000368:Aged; D002369:Castration; D003593:Cytoplasm / Q000473:pathology; D006801:Humans; D007984:Leydig Cell Tumor / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D013736:Testicular Neoplasms / Q000473:pathology* / Q000648:ultrastructure; D013737:Testis / Q000473:pathology