Diagnosis: Sertoli cell tumor.

Comment: A clue for the diagnosis of this particular tumor is the presence in some areas of cells with intracytoplasmic lipid (Fig. 5) reminiscent of the estrogenic lipid-rich Sertoli cell tumors of the canine testis (See Case 271). The presence of pleomorphism and frequent atypical mitoses (Fig.4) is consistent with a possible malignant course.