Is ICD-10-CM code C21 billable?

No, C21 (Malignant neoplasm of anus and anal canal) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code C21 belong to?

C21 belongs to Chapter 2 of the ICD-10-CM tabular list: C00–D49 (Neoplasms).

C21

Non-Billable

ChapterC00–D49

Rankcategory

Description

Malignant neoplasm of anus and anal canal

About ICD-10-CM code C21

Malignant neoplasm of anus and anal canal is classified in ICD-10-CM as code C21, part of C00-D49 Neoplasms, within Malignant neoplasms of digestive organs (C15-C26). Its status is non-billable, meaning reporting it requires a deeper, more specific code.

Use a more specific code (4 billable)

C21.0Malignant neoplasm of anus, unspecified C21.1Malignant neoplasm of anal canal C21.2Malignant neoplasm of cloacogenic zone C21.8Malignant neoplasm of overlapping sites of rectum, anus and anal canal

Metadata & Insights

•Non-billable category (requires more specific sub-code).
•Chapter 2: Neoplasms (C00-D49).

C15-C26 Parent Instructions

Excludes1(Not coded here. Use a different code.)

Kaposi's sarcoma of gastrointestinal sites (C46.4)

Excludes2(Not included here. Code separately if applicable.)

gastrointestinal stromal tumors (C49.A-)

Instructional Notes

Excludes2(Not included here. Code separately if applicable.)

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)

Clinical Hierarchy

BillableHas subcodes

CH2Neoplasms (C00-D49)

C15-C26Malignant neoplasms of digestive organs (C15-C26)

C21Malignant neoplasm of anus and anal canalNot billable

C21.0Malignant neoplasm of anus, unspecifiedBillable

C21.1Malignant neoplasm of anal canalBillable

C21.2Malignant neoplasm of cloacogenic zoneBillable

C21.8Malignant neoplasm of overlapping sites of rectum, anus and anal canalBillable

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to C21:

blockC15-C26

Malignant neoplasms of digestive organs (C15-C26)

View context instructions

MS-DRG Classification

2026

No direct MS-DRG triggers identified.

Cross Reference

Find Procedures (ICD-10-PCS)

Find surgical and procedural codes related to Malignant neoplasm of anus and anal canal.

Search PCS Codes