C21 Malignant neoplasm of anus and anal canal

The ICD-10-CM code for Malignant neoplasm of anus and anal canal is C21 (FY2026). It is a non-billable category code — select a more specific code below for claims.

Classification

Chapter

2: Neoplasms (C00-D49)

Section

C15-C26: Malignant neoplasms of digestive organs (C15-C26)

Category C21

5 codes (4 billable)

FY2026 Status

Stable since FY2024

Official Coding Guidelines

Tx of primary site (TOC entry)

a. Admission/Encounter for treatment of primary site ............................................................. 33

Tx of secondary site (TOC entry)

b. Admission/Encounter for treatment of secondary site .......................................................... 33

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool