[Treatment of dermatofibroma protuberans with fixed Mohs' micrographic surgery]. / Dermatofibrosarcome de Darier Ferrand: traitement par chirurgie micrographique de Mohs avec inclusion en paraffine.

ABSTRACT

INTRODUCTION: Dermatofibrosarcoma protuberans is a tumor of intermediate malignancy characterized by its aggressive local growth due to pseudopodium-like outgrowths and marked propensity to recur after surgical excision. To achieve complete cure with conventional surgery, surgical margins up to 5 cm are required, leading to wide scars. Mohs' micrographic surgery is used for the removal of certain malignant tumors, both ensuring complete excision by examination of all margins as well as minimizing normal tissue loss. However, differentiating minimal residual tumor from normal skin can be difficult on the frozen sections used in Mohs' micrographic surgery. Our aim was to develop a procedure of Mohs' micrographic surgery in conjunction with rush formalin-fixed, paraffin-embedded tangential sections. PATIENTS AND METHODS: Ten consecutive cases have been prospectively treated since 1998. Under local anesthesia, the tumor was first excised including lateral margin of 1 cm and a deep margin including the underlying muscle aponevrosis. A 2 to 3 mm thick horizontal section of the surgical bed was then removed, rush formalin-fixed, paraffin-embedded, tangentially sectioned, hematin-eosin stained, and eventually stained with an anti-CD34 monoclonal antibody. While waiting for pathology results, the surgical bed was not definitively closed. If excision was incomplete, an oriented complementary excision was performed. RESULTS: Excision was complete after the first stage in 7 patients and incomplete only deeply in 3. Lateral surgical margins were reduced to 1.3 cm in all patients, facilitating wound closure direct suture (5 patients), controlled wound healing (3 patients) or flap coverage (2 patients). No recurrence has been observed after a mean follow-up of 26 months. DISCUSSION: The use of Mohs' micrographic surgery in conjunction with rush formalin-fixed, paraffin-embedded tangential sections reduce surgical margins in dermatofibrosarcoma protuberans. This procedure would be interesting in difficult sites, such as the genitalia, the breast, or the periarticular regions. Other cases, and longer follow-up are however necessary to validate this promising technique.