Prognostic impact of fibrosarcomatous transformation in dermatofibrosarcoma protuberans: A cohort study

Background: Dermatofibrosarcoma protuberans (DFSP) is a rare, low-grade cutaneous malignancy that sometimes transforms into a high-grade fibrosarcomatous variant (DFSP-FS). Limited data compare clinical features and biological behavior of these 2 entities. Objective: We sought to compare clinical features and biological behavior of DFSP and DFSP-FS. Methods: This was a retrospective cohort study of ambulatory patients with DFSP or DFSP-FS treated between January 1955 and March 2012 in the dermatology department of a tertiary care academic medical center. Results: Of 188 patients, 171 (91%) had DFSP and 17 (9%) had DFSP-FS. Recurrence-free survival differed significantly between the groups over time (P = .002). The 1-year and 5-year recurrence-free survival was 94% and 86%, respectively, for DFSP, vs 86% and 42%, respectively, for DFSP-FS. Metastatic disease occurred in no patients with DFSP and in 18% (3 of 17) with DFSP-FS (P < . 001). There were no statistically significant differences in age at diagnosis, sex, race, symptomatology, maximum tumor size, muscle/bone invasion, or duration of tumor before diagnosis. Limitations: The retrospective nature of study was a limitation. Conclusions: DFSP-FS exhibits more aggressive behavior than DFSP, with lower recurrence-free survival and greater metastatic potential. Their similar clinical presentation mandates histopathological differentiation for prognosis.