Unusual metachronous isolated inguinal lymph node metastasis from adenocarcinoma of the sigmoid colon

This study aimed to describe an unusual case of metachronous isolated inguinal lymph nodes metastasis from sigmoid carcinoma. A 62-year-old man was referred to our department because of an obstructing sigmoid carcinoma. Colonoscopy showed the obstructing lesion at 30 cm from the anal verge and abdominal CT revealed a sigmoid lesion infiltrating the left lateral abdominal wall. The patient underwent a colonic resection extended to the abdominal wall. Histology showed an adenocarcinoma of the colon infiltrating the abdominal wall with iuxtacolic nodal involvement. Thirty three months after surgery abdominal CT and PET scan revealed a metastatic left inguinal lymph node involvement. The metastatic lymph node was found strictly adherent to the left iliac-femoral artery and encompassing the origin of the left inferior epigastric artery. Histology showed a metachronous nodal metastasis from colonic adenocarcinoma. Despite metastastic involvement of inguinal lymph node from rectal cancer is a rare but well known clinical entity, to the best of our knowledge, this is the first report of inguinal metastasis from a carcinoma of the left colon. Literature review shows only three other similar reported cases: two cases of inguinal metastasis secondary to adenocarcinoma of the cecum and one case of axillary metastasis from left colonic carcinoma. A metastatic pathway through superficial abdominal wall lymphatic vessels could be possible through the route along the left inferior epigastric artery. The solitary inguinal nodal involvement from rectal carcinoma could have a more favorable prognosis. In the case of nodal metastasis to the body surface lymph nodes from colonic carcinoma, following the small number of such cases reported in the literature, no definitive conclusions can be drawn