Popliteal sentinel lymph node involvement in melanoma patients.

Background: Sentinel lymph nodes (SLN) in popliteal basins are rare, and there is controversy in literature regarding their origin, management, and outcomes.

Objectives: To correlate clinical and pathological features of popliteal basin drainage and analyze the impact of popliteal lymph node drainage on survival.

Materials And Methods: Retrospective analysis of SLN biopsies performed at a single institution between 2000 and 2010.

Results: SLN biopsies were performed in 254 patients with melanoma in lower limbs, 247 of which were evaluated. In this group, there were 59 patients (24%) with a positive SLN. Twenty-seven cases (11%) presented with popliteal drainage, one of which lacked concurrent groin drainage. Among these 27 patients, three (11%) had popliteal metastasis, one of which had exclusive involvement of this basin. Popliteal drainage was associated with worse 5-year disease-free survival (DFS) (P = 0.028) but not 5-year overall survival (OS) (P = 0.219) in univariate analysis. In multivariate analysis, Breslow thickness, mitotic index, and positive SLN were prognostic factors for DFS. Only mitotic index correlated significantly with OS (P = 0.044).

Conclusions: Popliteal drainage seems to be associated with worse prognostic features of the primary tumor.