Extragastrointestinal stromal tumor originating from the vulva.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. They have gain-of-function mutations of the c-kit receptor tyrosine kinase gene and have been suggested to originate from the interstitial cells of Cajal. A small percentage of GISTs form extragastrointestinal masses. We report a rare case of a GIST originating from the vulva. A 55-year-old woman presented with a vulvar tumor. The tumor was initially diagnosed as a leiomyosarcoma following the first resection. Following a second recurrence the patient was administered chemotherapy. A third recurrence occurred and the patient underwent a third resection. Histology revealed that a bundle of fibrous tumor cells had invaded the connected tissue and muscular coat, and some spindle-shaped and blunt-ended nuclei were detected. Furthermore, immunohistochemical evaluation revealed that the tumor cells exhibited strong and diffuse staining for c-kit and CD34. The recurrent tumor was diagnosed as a GIST and a reevaluation of the original specimens also revealed a GIST. The patient was treated with imatinib, and is currently healthy with no evidence of recurrence at 20 months after the last surgery.