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Malignant Neoplasm of the Anus and Anal Canal B027

Last amended 
8 September 2022
Current RMA Instruments
Reasonable Hypothesis SOP
82 of 2022
Balance of Probabilities SOP
83 of 2022
Changes from previous Instruments

SOP Bulletin 232

ICD Coding
  • ICD-10-AM Codes: C21.0, C21.1, C21.2, D01.3
Brief description

This is a primary cancer of the lining of the anus/the anal canal.  The anal canal is approximately 3 cm long, extending from the end of the rectum (at the anorectal ring) to where the squamous mucosa blends with perianal skin.  There are three different histological types of mucosa in the anal canal - glandular, transitional, and non-keratinising squamous.  Squamous cell carcinoma is the most frequent cancer type.  Cancer of this area is uncommon.

Confirming the diagnosis

The diagnosis requires histology (or cytology for HSIL).

The relevant medical specialist is a colorectal surgeon.

Additional diagnoses covered by SOP
  • Adenocarcinoma of the anus / anal canal
  • Carcinoma-in-situ of the anus / anal canal
  • High-grade anal squamous intra-epithelial lesion (HSIL)
  • Squamous cell carcinoma of the anus / anal canal
Conditions not covered by SOP
  • Atypical squamous cells of undetermined significance#
  • Hodgkin’s lymphoma of the anus / anal canal*
  • Low-grade anal squamous intra-epithelial lesion (LSIL)#
  • Malignant melanoma of the anus / anal canal#
  • Malignant neoplasm of the anal margin (perianal skin)* - nonmelanotic malignant neoplasm of the skin SOP
  • Malignant neoplasm of perianal skin*
  • Malignant neoplasm of the rectum*
  • Non-Hodgkin lymphoma of the anus / anal canal*
  • Soft tissue sarcoma of the anus / anal canal*

* another SOP applies

# non-SOP condition

Clinical onset

The most common presentation is with bleeding, followed by pain or the sensation of a mass.  The condition may be asymsptomatic and found incidentally.  Bleeding may be attributed to another condition (e.g. haemorrhoids) which may delay diagnosis.

Clinical worsening

The only SOP worsening factor is for inability to obtain appropriate clinical management.  The condition is amenable to treatment.  Treatment options include combined chemoradiotherapy (without surgery), and local excision.