C21

ICD-10Non-billable category

Malignant neoplasm of anus and anal canal

Official ICD-10-CM descriptor (FY2026)

Malignant neoplasm of anus and anal canal

C21 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.

Excludes2

Not included here. The condition is not part of this code, but a patient may have both, and both codes may be reported together.

  • 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)

More specific codes under C21

Where this code sits

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Source

ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.

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