Mitotic rate as a predictive factor for positive sentinel lymph nodes in pT1 and pT2 melanomas

Sentinel lymph node biopsy is a crucial step in the management of patients affected by melanoma. The decision whether to perform it or not is based on different histological parameters, but the mitotic rate is no longer considered a prognostic variable after the release of the 8th edition of the American Joint Committee on Cancer (AJCC) guidelines. Our objective was to investigate the risk factors that increase the chance for sentinel lymph node positivity in melanomas with a Breslow thickness of less than 2.00 mm, including the mitotic count. A retrospective single-center study was performed on a homogenous cohort of 408 patients treated for cutaneous melanoma. Histological and clinical features were gathered and correlated with the increased risk for sentinel lymph node positivity by means of univariate and multivariate analyses. A statistically significant correlation between a high mitotic index and a positive sentinel lymph node was found in pT1 and pT2 patients, suggesting that in the case of pT1a melanoma with a high number of mitoses, a discussion about whether a sentinel lymph node biopsy is required should be done.