Anal cancer is a relatively rare neoplasm, representing approximately 1–2% of large bowel cancers. This malignancy is classified according to location: anal margin and anal canal. The former arise within keratinized, hair-bearing squamous epithelium distal to, but within 5 centimeters of, the anal verge. The primary lymphatic drainage of these tumors is to inguinal lymph nodes, less commonly to obturator or iliac nodes. Anal canal lesions arise within squamous and transitional epithelium, in an area which extends from the anal verge in a cephalad direction towards the top of the sphincter/puborectalis muscle complex. This zone spans a length of approximately 4 cm. The lymphatic drainage of these tumors is primarily to perirectal, mesenteric, and iliac nodes, less commonly to inguinal nodes although 15–20% of patients will initially present with inguinal metastases.
KeywordsAnal Canal Anal Verge Anal Cancer Inguinal Lymph Node Iliac Node
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