Background: The purpose of this study was to analyze available datasets to assess the degree of asymmetry typically associated with DFSP, and to study the optimal surgical approach for extirpating these tumors by clearing lateral margins.
Methods: MEDLINE (1994-2004) was searched for English-language multi-patient series concerning DFSP. Case series were included if complete information could be obtained for: (a) two-dimensional preoperative tumor size as measured on the skin surface before removal; (b) postoperative tumor size, as estimated by the dimensions of the final wound defect. Four case series met these criteria, and the authors were contacted directly for unpublished raw data.
Results: For each of 98 included tumors we computed: (1) the tumor index, a measure of clinically apparent tumor surface area; (2) clearance margin, or the theoretical best and worst-case surgical margins that would have been required for tumor clearance. We used this information to (a) assess the relationship between clinically apparent tumor size and final surgical margin; (b) determine the proportion of tumors of a given size that would be cleared by a margin of given width. We found that standard wide excision margin of 4 cm was predicted to provide a tumor clearance rate of 95% for tumors of preoperative size less than or equal to 3 cm x 3 cm.
Conclusions: There is a weak relationship between preoperative tumor size and the width of the final defect after clearance. Based on our calculations, very wide local excision is necessary for clearance of most DFSPs.