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

BACKGROUNDThe 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. OBJECTIVEThis 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 METHODSWe 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. RESULTSAlthough 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. CONCLUSIONA 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.