Granular cell myoblastoma of the vulva.

The granular cell myoblastoma (granular cell tumor) is a rare lesion of mesodermal origin that occurs in many areas of the body, including the vulva in seven percent of cases. The exact origin of this tumor is still being investigated. However, nerve cell origin is generally accepted. Lesions of the vulva occur in any age group and must be biopsied to rule out carcinoma, hidradenomas, sebaceous cysts, and papillomas. The recurrence rate of incompletely excised lesions is 25 percent. The microscopic picture of the lesion may simulate carcinoma as a result of reactive hyperplasia of the overlying epidermis. Discovery of a mass on the vulva in any patient which on biopsy reveals a granular cell myoblastoma should lead the examiner to excise the lesion completely and also to search for other lesions at various sites of the body.