Anal Canal and Perianal Skin
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Anal Canal and Perianal Skin (ICD‐O‐3 C21, ICD‐O‐3 C44.5) The anal canal extends from rectum to perianal skin (to the junction with hair‐bearing skin). It is lined by the mucous membrane overlying the internal sphincter, including the transitional epithelium and dentate line. Tumours of anal margin and perianal skin defined as within 5 cm of the anal margin (ICD‐O C44.5) are now classified with carcinomas of the anal canal.
The classification applies only to carcinomas. There should be histological confirmation of the disease and division of cases by histological type. The following are the procedures for assessing T, N, and M categories. T categories Physical examination, imaging, endoscopy, and/or surgical exploration N categories Physical examination, imaging, and/or surgical exploration M categories Physical examination, imaging, and/or surgical exploration
Regional Lymph Nodes The regional lymph nodes are the perirectal, the internal iliac, external iliac, and the inguinal lymph nodes.
TNM Clinical Classification T – Primary Tumour TX Primary tumour cannot be assessed T0 No evidence of primary tumour Tis Carcinoma in situ, Bowen disease, high‐grade squamous intraepithelial lesion (HSIL), anal intraepithelial neoplasia II–III (AIN II–III)
T1 Tumour 2 cm or less in greatest dimension T2 Tumour more than 2 cm but not more than 5 cm in greatest dimension T3 Tumour more than 5 cm in greatest dimension T4 Tumour of any size invades adjacent organ(s), e.g., vagina, urethra, bladder*
Digestive System
Rules for Classification