Atypical melanocytic nevi. Clinical and histopathologic predictors of residual tumor at reexcision

The appropriate method for surgical management of melanocytic lesions with disordered architecture and melanocytic atypia (formerly dysplastic nevi) has been controversial. Physicians often reexcise these lesions after primary removal because of their potential relation to malignant melanoma. The outcomes of these reexcisions and the original biopsy specimens have not been previously examined.

The purpose of this study was to examine reexcision specimens and their respective original specimens to determine whether there were any characteristics predictive of the presence of residual nevus cells (RNCs) on reexcision.

One hundred eighty-nine reexcision specimens of atypical melanocytic lesions were evaluated for this study. The original specimens were examined for specific histopathologic features without knowledge of the findings on reexcision. Clinical characteristics were also examined.

Of the 189 reexcision specimens, 47 (24.9%) contained RNCs. The proportion of specimens with RNC on reexcision was significantly greater if the original lesion was removed by punch biopsy rather than by shave or elliptical excision (38.3% vs 22.0% vs 10.5%, respectively; p < 0.03). Lesions located on the chest had a higher likelihood of RNCs than those on the back or leg (52.2% vs 21.7%; p = 0.009; 52.2% vs 9.7%, p < 0.002, respectively). Mean age was greater in those with RNCs at reexcision than those without (43.6 vs 37.9 years, respectively; p < 0.0001). The proportion of specimens with RNCs at reexcision was greater in those that had both lateral margins involved than in those that had nevus cells in either one or neither of the lateral margins in the original biopsy specimens (39.7% vs 24.0% vs 7.8%, respectively; p = 0.0005). One of the 189 reexcision specimens (0.5%) contained melanoma, although the original histopathologic diagnosis was an atypical melanocytic nevus.

We identified several clinical and histopathologic factors that are strongly associated with the presence of RNCs on reexcision.