The effect of dermoscopy in assisting on defining surgical margins of basal cell carcinoma.

To investigate the diagnostic value of dermoscopy in defining the tumor margin of basal cell carcinoma (BCC) for the appropriate surgical margin. A total of 107 BCC patients were enrolled for this study. The tumor boundaries were observed by naked eye and dermoscope respectively, and 5 mm outward was used as surgical margin according to the dermoscopy-defined margin. Pathological examinations were performed at 2 mm intervals in the direction previously marked and the effect was assessed accordingly. There were still 16.8% of patients whose visual margin was insufficient to the dermoscopy-detected margin. With 2 mm excision margin from the dermoscopy-guided tumor margin, excision range in 12 patients (11.2%) proved to be inadequate, but only 18 surgical margins (4.2%) in the whole 428 excision margin specimens proved to be tumor-positive. While with 4 mm margin, residual lesion was observed in 2 (0.5%) of 107 BCC patients, and positive margin was found in 2 (0.3%) of 428 margin specimen. There has been no recurrence in our study so far. Dermoscopy is superior to visual inspection for defining BCC tumor margin. Under preoperative dermoscopy detection, a 4 mm excision margin of BCC can achieve a radical resection rate of 98.1%, and 92.3% for a 2 mm excision margin of pigmented BCC.