A 10-year, single-institution analysis of clinicopathologic features and sentinel lymph node biopsy in thin melanomas

BackgroundThe 2009 American Joint Committee on Cancer criteria for thin cutaneous melanomas recommend staging sentinel lymph node (SLN) biopsy (SLNB) for select stage IB tumors. SLNB in this population remains controversial because of low rates of node positivity and inconsistent prognostic parameters.ObjectiveThe purpose of this study was to examine the association between multiple clinicopathologic features and SLNB result, and clinical outcome.MethodsClinical and pathologic parameters from patients with melanomas less than or equal to 1.00 mm receiving wide local excision with SLNB at our institution from 2001 through 2010 were recorded. Analysis for any statistically significant relationships between recorded parameters and SLN results and outcome were performed.ResultsA total of 189 cases yielded 3 positive SLNBs (1.6%). Disease progression occurred in 6 cases (3.2%). Positive SLNB predicted distant metastasis and death from disease (P = .0017). Mitotic rate was not associated with a positive SLNB result.LimitationsThe follow-up time for this study was limited (mean = 40.7 months).ConclusionOur data confirm a statistically significant relationship between SLNB result and likelihood for distant metastasis in thin melanoma. There was a trend for a relationship between mitotic rate and clinical outcome. This relationship reached statistical significance at a mitotic rate of greater than 3 mitoses/mm2.