Dermatofibrosarcoma protuberans of the head and neck: treatment with Mohs surgery using inverted horizontal paraffin sections

OBJECTIVE: To describe results of treating dermatofibrosarcoma protuberans of the head and neck with a Mohs surgical technique in which tumor margins were evaluated with inverted horizontal paraffin sections to identify the margin of resection necessary to achieve tumor-free borders. STUDY DESIGN: Retrospective case study of nine patients. METHODS: In each case, Mohs surgery using inverted horizontal frozen-section analysis was continued until tumor-free margins were achieved. The tumor-free specimens collected during this procedure were immediately reprocessed by using inverted horizontal paraffin sectioning, and the histological results of the two techniques were compared. To identify the margins of resection needed to achieve tumor-free margins, preoperative lesion size was compared with postoperative defect size. RESULTS: Paraffin section analysis showed persistent tumor in seven of the nine patients in whom the frozen-section technique was used to clear the tumor. Tumor-free margins were achieved in all patients by using one additional excision. The tumor had spread extensively beyond clinical margins and required a mean minimum margin of 3.7 cm around the gross area of tumor (margin range, 2.5-6.0 cm). Patients treated by this technique showed no local, regional, or distant recurrence at follow-up performed at a mean time of 43 months postoperatively (range, 19-74 mo). CONCLUSIONS: Dermatofibrosarcoma protuberans of the head and neck is a tumor that shows extensive infiltration beyond gross margins. Wide local excision with 2- to 3-cm margins results in an unacceptably high recurrence rate; larger excisional margins are necessary to remove all disease. Accurate margin identification achieved by using Mohs surgery with rush paraffin section analysis results in complete tumor removal and excellent control rates. This method should be preferred for treatment of dermatofibrosarcoma protuberans of the head and neck.