Abstract
BACKGROUND: Inguinal lymph node metastasis from rectum is uncommon but well-known occurrence, whereas that from colon adenocarcinoma is extremely rare. Inguinal lymph node metastasis from colon adenocarcinoma has only been reported in previous cases involving primary tumor invasion of the abdominal wall, or in those involving colon cancer metastasis to external iliac lymph nodes. We describe a case of inguinal lymph node metastasis from colon cancer without primary tumor invasion to the abdominal wall. CASE PRESENTATION: A 42-year-old female, who had undergone twice cesarean sections before, underwent open sigmoidectomy for sigmoid colon adenocarcinoma and received 12 cycles of FOLFOX regimen as adjuvant chemotherapy. Two years after sigmoidectomy, a follow-up CT scan revealed enlarged inguinal lymph nodes as well as growth of enhanced mass lesions on the abdominal wall at site of the cesarean section scar. Biopsy of both lesions revealed well-differentiated adenocarcinoma, and immunohistochemistry demonstrated positive expression of CDX2, substantiating its gastrointestinal origin. We therefore performed dissection of left inguinal lymph nodes and mass lesion of the abdominal wall. The patient died 51 months after lymph node dissection. CONCLUSIONS: This is the first reported case of inguinal lymph node metastasis from colon cancer without invasion of the primary tumor to the abdominal wall or without involvement of the external iliac lymph nodes, suggesting that the pathway of inguinal metastasis originated from the abdominal wall metastasis. When inguinal lymph node metastasis from colon cancer is suspected, if an R0 resection was possible, inguinal lymph node dissection may be a potentially effective treatment.