C21 vs C44.510
C21 (Malignant neoplasm of anus and anal canal) compared with C44.510 (Basal cell carcinoma of anal skin), from the official CMS tabular data. Both may be reported when both conditions are documented (Excludes2).
Can these codes be reported together?
Yes, when both are documented. C21 carries an Excludes2 note covering C44.510: “other and unspecified malignant neoplasm of anal margin (C44.500, C44.510, C44.520, C44.590)”
Excludes2 marks distinct conditions — both may be reported when both are documented.
Yes, when both are documented. C21 carries an Excludes2 note covering C44.510: “other and unspecified malignant neoplasm of anal skin (C44.500, C44.510, C44.520, C44.590)”
Excludes2 marks distinct conditions — both may be reported when both are documented.
Yes, when both are documented. C21 carries an Excludes2 note covering C44.510: “other and unspecified malignant neoplasm of perianal skin (C44.500, C44.510, C44.520, C44.590)”
Excludes2 marks distinct conditions — both may be reported when both are documented.
Side by side
| C21Malignant neoplasm of anus and anal canal | C44.510Basal cell carcinoma of anal skin | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Malignant neoplasm of anus and anal canal is a non-billable ICD-10-CM category code (C21). | Basal cell carcinoma of anal skin is a billable ICD-10-CM diagnosis code (C44.510). |
| Includes | — | malignant neoplasm of sebaceous glands malignant neoplasm of sweat glands Basal cell carcinoma of anal margin Basal cell carcinoma of perianal skin |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources