Lymphatic drainage of the anal canal differs above and below the dentate line, which determines the pattern of nodal spread of anal cancers. Carcinoma arising below the dentate line spreads primarily to which nodal basin?

• A Superior rectal nodes along the inferior mesenteric vessels
• B Internal iliac nodes
• C Para-aortic nodes directly
• D Superficial inguinal nodes ✓

Explanation

Below the dentate line, lymph drains with the inferior rectal vessels to the internal pudendal system and then to the superficial inguinal nodes, making inguinal node examination essential in low anal and perianal malignancies. Above the dentate line, drainage follows the superior rectal pathway to inferior mesenteric nodes and also communicates with internal iliac and para-aortic chains. This split explains differing spread patterns across the pectinate line.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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