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

Vulva cancers constitute approximately 5% of all gynecological malignancies and more than 90% of them are squamous cell carcinomas (1). Primary malignant mesenchymal tumors of the vulva are very rare. They are frequently located in the labium majus (2). There are only 5 cases of peripheral nerve sheath tumor of the vulva reported until now (3-7). Epitheloid type malignant peripheral nerve sheath tumors (MPNST) constitute less than 5% of all MPNSTs. They are commonly seen in patients between 2050 years old. The cases reported in the literature mostly arise in association with the major nerves including the sciatic nerve, tibial nerve, peroneal nerve, fascial nerve and digital nerves. Epitheloid type MPNSTs share some common features with carcinomas and melanomas. The most characteristic appearance is short cords of large epitheloid cells arranged in a vague nodular pattern. The tumor cells usually have prominent nucleoli similar to melanoma cells. The tumors may appear myxoid or cellular depending on the accumulation of acid mucin. Immunostaining for the antigens like S-100 and Leu-7 aid in showing the nerve sheath origin of the tumor. Fifty to ninety percent of MPNSTs display focal positivity for S-100 protein. About 80% of epitheloid type MPNSTs are strongly and diffusely positive for S-100 protein (8). ABSTRACT