C21
Header — not billableMalignant neoplasm of anus and anal canal
The ICD-10 code for malignant neoplasm of anus and anal canal is C21.
C21 is a non-billable header code. It groups related conditions but cannot be used on its own for reimbursement — select one of the 4 more specific codes below.
Clinical notes
Excludes2 (not included here)
An Excludes2 note means the excluded condition is not part of this one, but a patient can have both at the same time — in that case 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)
Documentation support
General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.
- •This is a non-billable header code. Documentation must support a more specific child code before this diagnosis can be reported on a claim.
- •As a general rule, code to the highest level of specificity supported by the documentation in the medical record.
Related codes in this category
- C15Malignant neoplasm of esophagusnon-billable header
- C16Malignant neoplasm of stomachnon-billable header
- C17Malignant neoplasm of small intestinenon-billable header
- C18Malignant neoplasm of colonnon-billable header
- C19Malignant neoplasm of rectosigmoid junction
- C20Malignant neoplasm of rectum
- C22Malignant neoplasm of liver and intrahepatic bile ductsnon-billable header
- C23Malignant neoplasm of gallbladder
- C24Malignant neoplasm of other and unspecified parts of biliary tractnon-billable header
- C25Malignant neoplasm of pancreasnon-billable header
- C26Malignant neoplasm of other and ill-defined digestive organsnon-billable header
- C21Malignant neoplasm of anus and anal canalnon-billable header