Background: Previous studies described various criteria in sentinel lymph nodes (SLN) of melanoma patients that predict the involvement of further, nonsentinel lymph nodes (NSLN). Such criteria may facilitate the selection of patients who might benefit from a completion lymph node dissection (CLND). However, it is currently unclear which parameters are most important.
Methods: A total of 180 melanoma patients with positive SLNB and subsequent CLND were investigated. Histopathologic parameters in the SLN were systematically evaluated and compared with regard to NSLN positivity. Twenty-eight of these patients (16.0%) had positive NSLN.
Results: By univariate analysis several criteria with regard to tumor burden and location of melanoma cells in the SLN correlated with NSLN involvement, such as positivity by hematoxylin-eosin (H&E) staining (P < .001), largest diameter of clusters (P < .001), capsular involvement (P = .001), extranodal extension (P < .001), and tumor penetrative depth (P < .001). Multivariate analysis revealed three independent parameters: (1) positivity of the SLN by H&E staining (versus by immunohistochemistry alone), (2) relative tumor burden > 10% of total lymph node tissue, and (3) perinodal intralymphatic tumor. In 23 of 28 patients with positive NSLN the SLN was positive by H&E staining, in 15 of 28 patients the relative tumor burden was > 10%, and 13 of 28 showed perinodal intralymphatic tumor. In 5 of 28 patients with NSLN involvement, these three parameters were negative.
Conclusions: Histopathologic examination of the SLN can identify patients at risk for NSLN positivity.