Frequency of residual melanoma in wide local excision (WLE) specimens after complete excisional biopsy

Objective: We sought to better understand the role of wide local excision (WLE) in the treatment of cutaneous melanoma by analyzing residual or locally metastatic disease in WLE specimens of melanomas initially diagnosed with a complete excisional biopsy. Methods: This was a retrospective review of 807 consecutive WLEs of melanomas diagnosed after complete excisional biopsy. All specimens were reviewed by a single dermatopathologist. Risk of residual or locally metastatic disease was analyzed using univariate and multivariate logistic regression models. Results: In the 807 WLE specimens, further melanoma was found in 34 cases (4.2%; 95% confidence interval [CI] 2.9-5.8). Residual primary melanoma was found in 33 of these. On univariate analysis, features associated with residual or locally metastatic disease were histologic subtype (odds ratio 3.0; 95% CI 1.3-7.1, P = .01) and tumor location (odds ratio 7.3; 95% CI 2.0-26.6, P < .01). On multivariate analysis, lentigo maligna was independently associated with melanoma remaining in WLE specimens (odds ratio 2.7; 95% CI 1.0-7.3, P = .04). Conclusion: Residual melanoma in WLE specimens after histologically assessed complete excisional biopsy is not uncommon. Patients with lentigo maligna subtype melanomas are most at risk. Our findings indicate that the procedure of WLE is most important therapeutically for its role in controlling the primary tumor, rather than in preventing local metastatic recurrence.