Prevalence of High-Risk Prostate Cancer Metastasis to Cloquet's Ilioinguinal Lymph Node.

Abstract

Cloquet's node, located at the junction between the deep inguinal nodes and the external iliac chain, is easily accessible and commonly excised during pelvic lymph node dissection for prostate cancer. However, we hypothesize that Cloquet's node is not part of lymphatic metastatic spread of prostate cancer. Between September 2016 and June 2019, 105 consecutive patients with high-risk prostate cancer (cT3a or Grade Group 4/5, or prostate specific antigen >20 ng/ml) underwent a laparoscopic radical prostatectomy and pelvic lymph node dissection. First, Cloquet's node was identified, retrieved and submitted separately to pathology as right and left Cloquet's node. Next, a pelvic lymph node dissection was completed including the external iliac, obturator fossa and hypogastric nodal packets. Each lymph node was cut into 3 mm slices which were separately embedded in paraffin, stained with hematoxylin and eosin, and examined microscopically. The final analysis included 95 patients. In this high-risk population, the median number of nodes removed was 22 (IQR 18-29); 39/95 patients (41%) had lymph node metastasis. The median number of Cloquet's nodes removed was 2 (IQR 2-3). Cloquet's node was negative in all but 1 patient (1.1%), who had very high-risk features and high metastatic burden in the lymph nodes. In high-risk prostate cancer, metastasis to the ilioinguinal node of Cloquet is rare. Given this low prevalence, Cloquet's node can be safely excluded from the pelvic lymph node dissection template.