Dermatofibrosarcoma protuberans: margins reduction using slow-Mohs micrographic surgery. Experience with 35 patients

Introduction: Dermatofibrosarcoma protuberans (DFSP) is a potentially malignant dermal mesenchymal tumour with a high risk of local recurrence. DFSP presents a sprawling appearance whose complete excision requires important margins. DFSP was initially resected with a 5cm excision margins, and more recently 3cm then 2cm margins were recommended. Mohs micrographic surgery (MMS) helps reduce these margins thanks to a 3-dimensional excision around the tumour, which is analysed in its entirety. We used the modified MMS called slow-MMS and tried every time it was possible to perform direct closure.

Methods: Thirty-five patients presenting a DFSP between 2004 and 2013 within the Plastic Surgery unit at Claudius Regaud Institute were included in this retrospective study. The patients were treated with slow-MMS using paraffin-embedded sections.

Results: One surgery was necessary for 72% of patients. For 17%, we had to perform a second surgery, and for 11% a third one. Our median clinical excision margins was 17mm (range 9.0:30.0). After a median follow-up of 46 months (range 35.2:60.2), we didn't observe any recurrence. Only one case required a local flap; for the others, the loss of substance was resolved with a direct closure.

Conclusion: Slow-MMS enabled a local control of the margins without recurrence at 46 months in our series. Besides, it helps performing smaller margins than wide excision and thus preserving the tissues. In our opinion, this is the treatment of choice regarding DFSP for which tissue sparing is essential. It seems particularly appropriate near functional areas or on the face.