A retrospective study addressed to understanding what predicts severe histological dysplasia/early melanoma in excised atypical melanocytic lesions

BACKGROUND: Atypical naevi are common benign skin lesions but are also recognized both as precursors of and risk factors for melanoma. It is therefore imperative to excise those lesions that are either likely to progress or are already progressing to melanoma. Clinically, however, it may be difficult to distinguish these from benign atypical naevi with bland histology. OBJECTIVES: To analyse the clinical characteristics of excised melanocytic lesions and to identify the predictors of severe histological atypia/melanoma in situ and invasive melanoma. METHODS: The case notes of 434 patients who had melanocytic lesions removed at a pigmented lesion clinic were studied retrospectively. A single pathologist reviewed the excised lesions and clinical characteristics predictive of malignancy were identified. RESULTS: The best predictors of melanoma were older age, history of change and site on an extremity, but only older age was predictive of severe histological atypia/melanoma in situ as opposed to mild to moderate atypical histology. CONCLUSIONS: These results confirm the difficulty of differentiating accurately between benign atypical naevi and borderline lesions or early melanoma in a clinical setting. It is therefore necessary to have a sufficiently low threshold for excision to avoid missing early melanomas, particularly in older patients presenting with lesions on the extremities.