C21.0 – Malignant neoplasm of anus, unspecified
ICD-10-CM 2027 diagnosis code · Malignant neoplasms of digestive organs
ICD-10-CM code
C21.0
- Code
C21.0(claims format:C210)- Description
- Malignant neoplasm of anus, unspecified
- Billable
- Yes – valid for HIPAA-covered transactions
- Valid for
- Dates of service October 1, 2026 – September 30, 2027 (FY2027)
- Chapter
- 2. Neoplasms (C00-D49)
- Block
- C15-C26 Malignant neoplasms of digestive organs
- Parent codes
- C21
Notes inherited from parent codes
Instructional notes at a category or block level apply to every code below it.
C21 – Malignant neoplasm of anus and anal canal
Excludes2 (not included here):
- 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)
Block C15-C26
Excludes1 (not coded here):
- Kaposi's sarcoma of gastrointestinal sites (C46.4)
Excludes2 (not included here):
- gastrointestinal stromal tumors (C49.A-)
Index terms for C21.0
Entries in the ICD-10-CM alphabetic index that lead to this code:
Related codes in C21
Frequently asked questions
What is ICD-10 code C21.0?
C21.0 is the ICD-10-CM code for malignant neoplasm of anus, unspecified, in the block C15-C26 (Malignant neoplasms of digestive organs).
Is C21.0 a billable code?
Yes. C21.0 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.
What category does C21.0 belong to?
It belongs to category C21 – Malignant neoplasm of anus and anal canal.
Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.