Differentiation

Background: Dermatofibrosarcoma protuberans with fibrosarcomatous differentiation (DFSP-FS) is a rare variant of DFSP with a more aggressive clinical course, characterized by higher rates of local recurrence, metastasis, and death. Methods: We conducted a clinicopathologic review of all DFSP-FS cases that occurred in Alberta, Canada, from 1997 to 2007. Results: Of the 75 DFSP cases reviewed, 4 demonstrated fibrosarcomatous differentiation. Three patients were female and one was male, and the age range was 25 to 76 years. Three tumors invaded to skeletal muscle, whereas one invaded to subcutaneous tissue only. Although perineural invasion was noted in all four cases, none exhibited lymphovascular space invasion. One local recurrence developed, and two of four tumors metastasized. Metastasis was associated with tumor size, tumor necrosis, grenz zone involvement, ulceration, thickness, and tumor grade. One patient died within 5 years of diagnosis. Conclusion: DFSP-FS represents a more aggressive subtype of DFSP. Several features of DFSP-FS may impart a higher risk of metastasis. Contexte: Le dermatofibrosarcome de Darier-Ferrand (DDF) avec différenciation fibrosarcomateuse (DFS) est une variante rare du DDF, qui connaı̂t une évolution clinique plus défavorable et qui comporte des taux plus élevés de récidive locale, de métastase et de mortalite ́ que la forme simple. Méthode: Nous avons procéde ́ a ̀ un examen clinicopathologique de tous les cas de DDF-DFS, relevés en Alberta, au Canada, de 1997 a ̀ 2007