Treatment of dermatofibrosarcoma protuberans with fixed Mohs' micrographic surgery: A French cohort prospective study

Abstract

Background

Dermatofibrosarcoma protuberans (DFSP) presents a high recurrence rate after conventional excision. Mohs' micrographic surgery (MMS) ensures complete excision and minimal normal tissue loss. However, discriminating between residual tumor and normal skin can be difficult on frozen sections compared with fixed paraffin sections.

Objectives

To develop a MMS procedure in conjunction with fixed paraffin sections to treat DFSP with reduced lateral margins and to evaluate the long-term recurrence rate in a consecutive series of DFSP patients.

Methods

We prospectively collected 223 consecutive cases of DFSP (206 primary and 17 recurrent) treated with fixed-MMS between October 1998 and December 2014 in our skin cancer referral center. Follow-up was provided until October 2020. The fixed-MMS was favored to treat DFSP due to the frequent large size of MMS layer, which made analysis of frozen sections difficult. Determined on the basis of publications on MMS in DFSP, we decided to proceed with a first stage of fixed MMS including a 13 mm lateral margin and a deep margin extending to the underlying muscle fascia.

Results

Most patients (N = 196; 87.9 %) had a complete resection after the first stage. In cases with incomplete resection (N = 27; 12.1 %), only the deep margin was involved in most cases (N = 21/27; 77.8 %). Complete resection was always achieved with a second (N = 23) or third or more stages (N = 3). Only one local recurrence was observed (after 85.3 months) with a median follow-up of 63.9 months [4.4–243.9].

Conclusions

We report the largest cohort of DFSP treated with fixed-MMS. Only one tumor recurred (0.4 % recurrence rate).