[Fibrosarcomatous dermatofibrosarcoma protuberans: a clinicopathological analysis of 12 cases]

To investigate the clinical pathological features of fibrosarcomatous dermatofibrosarcoma protuberans (FS-DFSP).

The clinical history, histopathological features and immunohistochemical characteristics were analyzed in twelve cases of FS-DFSP from January 1997 to February 2011, and related literature were reviewed.

Age of the patients (2 females, 10 males) at diagnosis ranged from 41 to 70 years (mean 53 years). Among the 12 cases of FS-DFSP, 9 cases aroused in recurrent ordinary DFSP. Histologically, FS areas in FS-DFSP were characterized by a fascicular and highly cellular histology, frequently showing a characteristic herringbone pattern. FS-DFSP showed diminishment of CD34 staining in FS areas. The labeling index of Ki-67 was much higher in the FS areas (10%-40%) than that in the conventional DFSP areas (2%-5%). All the patients were treated by operation with local excision or wide excision. Postoperative radiotherapy and chemotherapy was administered in two cases respectively. Follow-up information in 9 of 12 patients (9 to 86 months) revealed local recurrence in 6 patients. Distant metastases were seen in two patients. One patient was died in the follow up period.

FS-DFSP is a rare and unique subtype of DFSP and is associated with significant elevated risk of both local and distance metastasis, usually followed by poor outcome. Compared to ordinary DFSP as a borderline neoplasm, FS-DFSP should be considered as a malignant tumor.