A 62-year-old man has a fungating growth at the anal verge. Biopsy confirms adenocarcinoma arising below the dentate line. To which group of nodes would this tumour first spread?

• A Superior rectal nodes along the inferior mesenteric artery
• B Superficial inguinal nodes ✓
• C Internal iliac nodes
• D Paraaortic nodes directly

Explanation

Below the pectinate line the anal canal drains to the inferior rectal veins and its lymphatics follow to the superficial inguinal nodes, so a low anal cancer presents with inguinal nodal enlargement. Above the pectinate line drainage is upward to the superior rectal and inferior mesenteric nodes, which kills option A. Internal iliac nodes receive lymph mainly from mid-rectum and pelvic viscera, not the cutaneous lower canal.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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