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ICD-10-CM 2027 diagnosis code

C21.2Malignant neoplasm of cloacogenic zone

✓ Billable / specificCC — complication/comorbidity

C21.2 is a valid, billable ICD-10-CM code for malignant neoplasm of cloacogenic zone. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About C21.2

C21.2 is the ICD-10-CM diagnosis code for malignant neoplasm of cloacogenic zone. It belongs to category C21 (malignant neoplasm of anus and anal canal), block C15-C26 (malignant neoplasms of digestive organs) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within C21 (malignant neoplasm of anus and anal canal), C21.2 is specifically for malignant neoplasm of cloacogenic zone. Related codes cover anus, unspecified (C21.0), anal canal (C21.1) and overlapping sites of rectum, anus and anal canal (C21.8).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 374 (Digestive Malignancy with MCC, relative weight 2.1109), DRG 375 (Digestive Malignancy with CC, relative weight 1.1838) and DRG 376 (Digestive Malignancy without CC/MCC, relative weight 0.8929), in MDC 06 (Diseases and Disorders of the Digestive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 154.8 (malignant neoplasm of other sites of rectum, rectosigmoid junction, and anus).

Notes that apply from higher levels

Instructions written at a parent level also apply to C21.2.

› From C21 Malignant neoplasm of anus and anal canal
Excludes2

Broader instructions also apply from C15-C26 Malignant neoplasms of digestive organs and Chapter 2: Neoplasms.

Alphabetic index entries

1 entries

Terms in the official ICD-10-CM index that lead to C21.2.

Table of Drugs & Neoplasms entries

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 154.8Malignant neoplasm of other sites of rectum, rectosigmoid junction, and anusapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about C21.2

Is C21.2 billable?

Yes. C21.2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can C21.2 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict C21.2 as a principal diagnosis.

Is C21.2 a CC or MCC?

C21.2 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does C21.2 group to?

C21.2 is used in the MS-DRG v44.0 logic for MS-DRG 374 (Digestive Malignancy with MCC), MS-DRG 375 (Digestive Malignancy with CC) and MS-DRG 376 (Digestive Malignancy without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for C21.2?

The CMS General Equivalence Mappings map C21.2 to ICD-9-CM 154.8.