Mitotic Rate for Thin Melanomas: Should a Single Mitotic Figure Warrant a Sentinel Lymph Node Biopsy?

BACKGROUND The seventh edition of the American Joint Committee on Cancer guidelines recognize mitotic rate (MR) as a component of the staging criteria for cutaneous melanomas with a Breslow depth <= 1 mm. OBJECTIVE This review discusses the evidence behind the threshold of 1 mitosis per square millimeter as a prognostic variable in thin melanomas, particularly because it relates to the decision to pursue a sentinel lymph node biopsy (SLNB). MATERIALS AND METHODS We performed a systematic review using the PubMed database to identify articles that contain prognostic information for thin melanomas based on MR and sentinel lymph node (SLN) status. RESULTS Although the threshold of a single mitosis correlates with a statistically significant decrease in survival rates for patients with thin melanomas, the clinical relevance remains questionable particularly because it relates to the decision to pursue an SLNB. CONCLUSION A single mitosis in thin melanomas does not increase the risk of a positive SLN so much that SLN biopsy should be routinely performed for this cohort.