The inadequacy of punch-excised melanocytic lesions: sampling through the block for the determination of "margins".

Background Dermatopathologists often are asked by clinicians to report margins on punch excisions of melanocytic lesions. Objective We sought to determine the adequacy of surgical margins on melanocytic lesions submitted with intention of complete excision using punch removal technique. Methods We conducted prospective analysis of surgical margins on 266 consecutive patients who underwent attempted complete removal of 405 melanocytic nevi submitted as punch and fusiform excisions. Results Of 206 nonbisected punch excisions, 127 (62%) had final positive margins. Of 159 bisected punch excisions, 76 (48%) had final positive margins. Of 40 elliptical excisions, two (5%) had final positive margins. Limitations Information on the perilesional rim of nonpigmented skin included in the excision was not available. Conclusions Of punch excisions, 56% had positive margins. Importantly, 30% of these punch excised specimens were negative on initial levels but had positive margins after extensive sectioning, affirming that fusiform excisions are the preferred method to evaluate margins in melanocytic lesions.