Malignant neoplasm of anus and anal canal (C21) ICD-10-CM
The C21 code range covers malignant neoplasm of anus and anal canal with 5 ICD-10-CM diagnosis codes. 4 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
- malignant carcinoid tumors of the colon C7A.02
- malignant melanoma of anal margin C43.51
- malignant melanoma of anal skin C43.51
- malignant melanoma of perianal skin C43.51
- other and unspecified malignant neoplasm of anal margin C44.500 C44.510 C44.520 C44.590
- other and unspecified malignant neoplasm of anal skin C44.500 C44.510 C44.520 C44.590
- other and unspecified malignant neoplasm of perianal skin C44.500 C44.510 C44.520 C44.590
Codes in the C21 Range 5 codes · 4 billable
About the C21 Code Range
The ICD-10 codes C21 through C21.8 classify various types of malignant tumors affecting the anus and anal canal. These codes are specifically used to document cancers located in different areas such as the anus, anal canal, cloacogenic zone, and overlapping sites of the rectum and anus.
The section includes codes like C21.0 for unspecified malignant neoplasm of the anus, covering terms such as lymphoma of the anus, adenocarcinoma, and carcinoma of the anus. C21.1 addresses malignant tumors in the anal canal, including primary carcinoma, Paget's disease of the anal canal, and malignant melanoma, providing detailed options for coding cancers specific to this site. C21.2 targets the cloacogenic zone, a distinct area near the anus where cloacogenic carcinoma may arise. Finally, C21.8 codes for cancers involving overlapping regions of the rectum, anus, and anal canal, which may be described as anorectal adenocarcinoma or tumors at the anorectal junction. Recognizing these synonyms and their corresponding ICD-10 codes is essential when coding for anal cancers to ensure precise documentation and treatment planning.
Questions About This Page
How many billable codes are in the C21 range?
Of the 5 codes in this range, 4 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the C21 range classify?
The range classifies malignant neoplasm of anus and anal canal. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
