Inguinopelvic Lymphadenectomy Following Positive Inguinal Sentinel Lymph Node Biopsy in Melanoma: True Frequency of Synchronous Pelvic Metastases

True frequency of synchronous pelvic metastases with positive inguinal sentinel lymph node (SLN) biopsy is unknown. Role of pelvic dissection in the SLN era is unclear.

From 1994 to 2004, 1 surgeon routinely performed nonselective, complete inguinopelvic lymphadenectomy after positive inguinal SLN biopsy. All cases were identified from a prospectively maintained database. Clinicopathologic features associated with pelvic disease were assessed.

A total of 40 patients with positive inguinal SLN underwent, without additional selection, 42 complete inguinopelvic lymphadenectomies. Median age was 46.5 years (range 25–79 years); 79% had lower extremity primaries. Median Breslow depth was 2.3 mm (range 1.0–10.0 mm), Clark’s IV/V 98%, ulceration 26%. Frequency of synchronous pelvic disease upon completion lymphadenectomy was 5 of 42 (11.9%). Patients with and without pelvic disease were similar in age, sex, Breslow depth, Clark’s level, ulceration, and mitoses. All 5 cases with pelvic metastases had extremity primaries (4 distal, 1 proximal). Of the 5, 3 (60%) had ≥3 total involved inguinal nodes, compared with only 1 (2.7%) of the 37 cases without pelvic disease (P = .003). Ratio of positive to total number inguinal nodes retrieved was >0.20 in 80% of cases with pelvic disease and 8.6% of cases without (P = .002). Upon lymphoscintigraphy review, secondary pelvic drainage was present in 80% of cases with pelvic disease compared with 56% of cases without pelvic disease, though the trend was statistically insignificant (P = .63).

In this cohort of unselected, SLN-positive patients with complete inguinopelvic lymphadenectomy, frequency of synchronous pelvic disease was 11.9%. Patients with ≥3 total involved inguinal nodes or inguinal node ratio >0.20 appear more likely to harbor pelvic disease.