Malignant peripheral nerve sheath tumor of the vulva. A case report.

BACKGROUND Malignant peripheral nerve sheath tumors (MPNSTs) are rare tumors in the head and neck, and their location in the genitalia, especially the vulva, is very rare. CASE An 81-year-old woman with a solid, round vulvar tumor, 2 cm in diameter, underwent a radical hemivulvectomy after recurrence of MPNST with no evidence of neural involvement or stigmata of neurofibromatosis. The tumor cells were positive for S-100 protein and negative for cytokeratin, actin smooth muscle, HMB45 and alpha-1-antitrypsin. The biopsy diagnosis was MPNST with clear surgical margins. The patient was followed for nine months after surgery, without evidence of disease. CONCLUSION MPNSTs constitute a small fraction of peripheral nerve tumors. Their site of origin, immunohistochemical staining pattern and ultrastructural morphology are thought to indicate a schwannian origin; however, the histogenesis of the tumor remains controversial. A definite relationship to a peripheral nerve may or may not be present. Diagnosis of MPNST is based on the pathologic appearance, immunohistochemistry and clinical features, such as predominant cell type (spindle cell), nerve involvement or differentiation, and association with neurofibromatosis disease. There have been few documented cases of MPNST arising in the vulva.