3D-Histological evaluation of surgery in dermatofibrosarcoma protuberans and malignant fibrous histiocytoma: differences in growth patterns and outcome.

AIMS: To evaluate the microscopic growth pattern of dermatofibrosarcoma protuberans (DFSP) and malignant fibrous histiocytoma (MFH) and the long-term outcome using 3D-histologic surgery with paraffin sections to cover complete margins and to detect subclinical spreads very sensitively.

METHODS: One hundred and one patients have been included comprising 70 DFSP, 31 MFH. Data from 87 patients treated since 1992 were collected prospectively.

RESULTS: Mean clinical tumor-size was 45 mm, mean histological tumor size 65 mm. A mean excision margin of 19 mm achieved negative margins. The histological infiltration shows an asymmetrical pattern with horizontal or vertical extension either cord-, sector- or multiple-like up to 70 mm in length, detectable by 3D-histology. Age and localization differed significantly between DFSP and MFH lesions. MFH tumors had a significantly deeper infiltration than DFSP. The mean follow up was 60 months. In 70 patients with DFSP one local recurrence after 62 months occurred, but no metastasis. 31 patients with MFH developed 8 local recurrences, and 4 metastases (lymph nodes and/ or lungs); 3 of them died of the disease, all 3 had a postoperative status of R1 (p=0.001).

CONCLUSIONS: There are significant differences in growth pattern and clinical outcome between DFSP and MFH. DFSP can be cured by surgery following 3D-histology with paraffin sections. MFH is significantly more malignant. After local R0-resection proofed by 3D-histology higher cure rates can be achieved.