Microscopic margins and results of surgery for dermatofibrosarcoma protuberans.

Background: Dermatofibrosarcoma protuberans is a rare low-grade sarcoma of the skin with a tendency to recur locally after inadequate excision. Treatment has traditionally been wide excision with a 2- to 3-cm gross margin. Because of the variable results presented in mainly retrospective reports, it has been queried whether local control can be as good with conventional surgery as with micrographic surgery.

Methods: Forty patients with dermatofibrosarcoma protuberans treated by surgical excision were operated on at our center from 1987 to 2001. Data were recorded prospectively. Twenty-seven patients presented with a primary tumor and 13 with a locally recurrent tumor primarily operated on elsewhere. Gross and histologic margins were studied in detail.

Results: At a mean follow-up of 40 months, there were no recurrences. Thirty-four patients required single, five patients two, and one patient three operations before the margins were adequate (mean, 1.2 stages per patient). Twenty-three patients (58 percent) needed reconstructions. Tumor-free margins were obtained in 39 patients. The average thickness of surgical gross margins was 3.1 cm; histologically defined margins averaged 1.6 cm.

Conclusions: Good local control can be achieved with wide surgery. Histologic tumor-free margins differ greatly from gross margins and are difficult to assess clinically and macroscopically. Careful postoperative histologic examination with margins measured in millimeters should be carried out to define the adequacy of excision in all directions. On average, a 1.6-cm histologic margin was adequate for complete local control. Most patients can be operated on in one stage. Reconstructions are often needed.