Is the node of Cloquet the sentinel node for the iliac/obturator node group?

PURPOSE Some surgeons question the survival advantage of ilioinguinal lymphadenecto my for metastatic melanoma because they believe that deep nodal involvement signifies a poor prognosis that is unchanged by surgery. However, several series, including our own, have reported 5-year survival rates reaching 30% . New adjuvant therapies may further improve survival after ilioinguinal ly mphadenectomy, but this applies only to nodal basins with metastatic diseas e. We hypothesized that the node of Cloquet accurately reflects the patholo gic status of the iliac/obturator nodes, allowing deep pelvic lymphadenecto my to be selectively performed. PATIENTS AND METHODS Between 1972 and 1998, 691 patients with primary cutaneous melanoma underwe nt both elective and therapeutic complete (superficial and deep) ilioinguin al lymphadenectomy. Of the 204 (30%) patients with tumor-positive inguinal and/or iliac/obturator nodes, 68 had a node of Cloquet identified during pa thologic review of the lymphadenectomy specimen. Chart and computer databas e review of these 68 patients mas undertaken to determine the association b etween the tumor status of Cloquet's node and that of deep pelvic nodes. Im munohistochemical analysis was performed on eight of 11 negative Cloquet's nodes in patients with positive iliac/obturator nodes. Paraffin blocks of t he other three negative nodes of Cloquet were unavailable for immunohistoch emistry, and they were excluded from analysis. RESULTS Tumor-positive deep nodes were identified in the lymphadenectomy specimen f rom 20 of 30 (67%) patients with a positive Cloquet's node and from eight o f 35 (23%) patients with a negative Cloquet's node (P= 0.0019). Re-examinat ion of these eight tumor-negative Cloquet's nodes using immunostaining with S-100 and HMB45 identified tumor in 3 nodes, increasing the sensitivity of Cloquet's node for predicting deep nodal metastases from 71% to 82%. The 6 .8 odds ratio of positive iliac/obturator nodes given a positive node of Cl oquet increased to 12.4 after immunohistochemical analysis. The positive an d negative predictive values were also enhanced from 67% to 70% and 77% to 84%, respectively. DISCUSSION The tumor status of the node of Cloquet significantly reflects the tumor st atus of the iliac/obturator nodes, particularly when Cloquet's node is exam ind by immunohistochemical analysis. The node of Cloquet assumes the role o f the sentinel node in patients whose superficial inguinal lymph nodes drai n through Cloquet's node to the iliac/obturator nodes.