Dermatofibrosarcoma protuberans of the vulva: a clinicopathologic and immunohistochemical study of 13 cases.

Dermatofibrosarcoma protuberans (DFSP) is a low-grade sarcoma seldom seen in the vulva with only 29 cases reported. We present the clinicopathologic and immunohistochemical features of 13 such cases seen in our institution over a period of 29 years (1978 to 2007). Patient age ranged from 23 to 76 years (mean, 46 y). Twelve patients had a vulvar mass. One patient presented with a pigmented skin lesion. Tumor size ranged from 1.2 to 15 cm (median, 4 cm). Microscopically, all the cases showed typical features of DFSP. In 1 case, myxoid changes were also noted; 3 cases showed fibrosarcomatous transformation. Of interest, in 7 of our 13 cases, a variety of diagnoses, such as cellular dermatofibroma, cellular leiomyoma, neurofibroma, low-grade leiomyosarcoma, fibrosarcoma, low-grade malignant schwannoma, desmoplastic melanoma, cellular neurofibroma, and low-grade malignant peripheral nerve sheet tumor were initially considered. All 11 cases tested for CD34 were positive, whereas 7/9 cases, 8/9 cases, and 9/9 cases were positive for PDGFR-alpha, PDGFR-beta, and c-abl, respectively. All patients were initially treated with excisional biopsy, wide local excision, or radical vulvectomy. Local recurrences occurred in 7 cases. One patient also developed distant metastases. All recurrences were treated surgically; 1 patient also received chemotherapy and radiotherapy and another received imatinib (Gleevec). Follow-up data ranging from 2 to 444 months was available for all patients. Nine patients had no evidence of disease, 2 patients were alive with disease, 1 patient had died of disease, and 1 patient had died of other causes. DFSP affects women of a wide age range and has a propensity to recur locally. The frequent expression of PDGFR-alpha, PDGFR-beta, and c-abl in these cases agrees with the findings of other investigators and supports the use of imatinib (Gleevec) in cases that are recurrent or not amenable to surgery.