A single-institutional review of 68 patients with dermatofibrosarcoma protuberans: wide re-excision after inadequate previous surgery results in a high rate of local control

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a cutaneous soft tissue sarcoma characterized by an indolent but aggressive local growth. Unplanned excisions with positive margins are common, and the prognostic impact of radical re-excisions is still unclear. The aim of the present study was to identify prognostic indicators of recurrence-free survival (RFS) in patients with DFSP through a long-term follow-up. We tried particularly to determine the prognostic impact of surgical margins and re-excisions in patients after earlier inadequate surgery. METHODS: Seventy-five patients with DFSP were treated surgically at our institution between 1999 and 2015. Analyses were restricted to 68 participants with available information on surgical margins. The median follow-up was 5.4 years. RESULTS: Fifty-four patients (79.4%) had low-grade DFSP and 14 patients (20.6%) intermediate-grade FS-DFSP. The 5-year RFS rates were estimated to be 93.5% (95% CI 81.2–97.9) for low-grade DFSP and 39.7% (95% CI 13.0–65.8) for FS-DFSP (P < 0.0001). Re-excisions were performed in 55 patients (80.9%) following R1 or marginal R0 resections. Negative margins could be attained in a total of 65 patients (95.6%). Negative margin widths >1 cm led to the best local outcome within the R0 subgroup. Significant adverse prognostic features in the multivariate analysis included histologic grade and close margins. CONCLUSIONS: The data from this study underscore the long-term benefit of negative margins. In our analysis, re-excisions were an effective method to achieve a high rate of local control in patients who presented after R1 or marginal R0 resection. To ensure the best outcome, re-excisions should aim at negative margin widths of more than 1 cm in the histologic specimen.