A sigmoid colon mass revealing adenocarcinoma would metastasize primarily to which lymph node group?

• A. Common iliac lymph nodes
• B. Inferior mesenteric lymph nodes
• C. Superior mesenteric lymph nodes
• D. Celiac lymph nodes

Answer: (B)

Lymphatic drainage patterns dictate where cancers spread. The sigmoid colon is part of the hindgut and is supplied by the inferior mesenteric artery, with lymphatics that travel along those vessels to the inferior mesenteric lymph nodes. These nodes are the first regional drainage site for this portion of the colon, so a sigmoid colon adenocarcinoma is most likely to metastasize there. The other nodal groups drain different regions (foregut to celiac, midgut to superior mesenteric, pelvic structures to common iliac), so they are not the primary drainage for the sigmoid colon.