C21

C21: Malignant neoplasm of anus and anal canal

Non-billable headerICD-10-CM

C21 is a non-billable header ICD-10-CM code for malignant neoplasm of anus and anal canal. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes2: not included here, but may coexist

The excluded condition is not part of this code, but a patient can have both. You may code both.

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)

Other codes that can never be billed with C21

Their own Excludes1 notes name this code, so the conflict is not listed above.

C44.5Other and unspecified malignant neoplasm of skin of trunk

Risk adjustment

No CMS-HCC V28 category: this code does not change a RAF score.

Code history

Unchanged in every release from FY2024 to FY2027.

Code to one of these instead C21

4 child codes. Green means billable.