Dermatofibrosarcoma protuberans of the vulva: a mesenchymal tumour with a broad differential diagnosis and review of literature.

Dermatofibrosarcoma protuberans (DFSP) is a malignant cutaneous soft tissue tumour, which rarely presents in the vulva. We report an unusual case of this tumour involving the vulva. A 61-year-old female presented with a mass in the left mons pubis. Subsequent excisional biopsy of the mass was performed. Histologic evaluation of the specimen showed a spindle cell lesion consisting of fibroblast-like cells arranged in a storiform pattern. On average, there were 2 to 3 mitotic figures per 10 high power field (hpf). The neoplastic cells showed extension into the surrounding fibroadipose tissue. A panel of immunohistochemical stains including CD34, S-100, melan-A, HMB-45, vimentin and smooth muscle actin (SMA) were tested. The neoplastic cells showed diffuse staining with CD34 and vimentin, while the rest were negative. Based on the morphologic and immunohistochemical staining pattern, a diagnosis of DFSP was rendered. The patient underwent two subsequent resections before she had clear resection margins. The postoperative course was unremarkable. The patient is disease free without recurrence after a follow-up of 12 months. DFSP infrequently involves the vulva and should be considered in the differential diagnosis of other spindle cell lesions presenting in this unusual site. The role of immunohistochemical staining with CD34 is imperative in establishing the diagnosis. The rate of local reoccurrence is high, but it rarely shows metastasis. Treatment of choice is wide local surgical excision with close follow-up to detect reoccur- rence.