Granular cell tumor of penis and scrotum.

Two cases of granular cell tumor of the external male genitalia are reported: one on the scrotum and one on the shaft of the penis. No previous reports of granular cell tumor of the scrotum appear in the literature. Each tumor was treated by simple excision and there was no recurrence. Each tumor showed cytoplasmic S-100 positivity. Tumor was seen in close proximity to small nerve fibers, sweat glands, and erectile smooth muscle. These findings are considered encroachments rather than evidence of origin from any of these structures. An immunohistochemical signature for granular cell tumor has developed in recent years, but, from a practical viewpoint, only the S-100 stain should be used for confirmation of the diagnosis.