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ICD-10-CM 2027 diagnosis code

C79.31Secondary malignant neoplasm of brain

✓ Billable / specificCC — complication/comorbidity

C79.31 is a valid, billable ICD-10-CM code for secondary malignant neoplasm of brain. 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 C79.31

C79.31 is the ICD-10-CM diagnosis code for secondary malignant neoplasm of brain. It belongs to category C79 (secondary malignant neoplasm of other and unspecified sites), block C76-C80 (malignant neoplasms of ill-defined, other secondary and unspecified sites) 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 C79.3 (secondary malignant neoplasm of brain and cerebral meninges), C79.31 is specifically for secondary malignant neoplasm of brain. Related codes cover cerebral meninges (C79.32).

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 054 (Nervous System Neoplasms with MCC, relative weight 1.5194) and DRG 055 (Nervous System Neoplasms without MCC, relative weight 1.0296), in MDC 01 (Diseases and Disorders of the Nervous 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 198.3 (secondary malignant neoplasm of brain and spinal cord).

Notes that apply from higher levels

Instructions written at a parent level also apply to C79.31.

› From C79 Secondary malignant neoplasm of other and unspecified sites
Excludes1
  • secondary carcinoid tumors (C7B.-)
  • secondary neuroendocrine tumors (C7B.-)

Broader instructions also apply from Chapter 2: Neoplasms.

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 →
  • 198.3Secondary malignant neoplasm of brain and spinal cordapproximate

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 C79.31

Is C79.31 billable?

Yes. C79.31 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can C79.31 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict C79.31 as a principal diagnosis.

Is C79.31 a CC or MCC?

C79.31 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does C79.31 group to?

C79.31 is used in the MS-DRG v44.0 logic for MS-DRG 054 (Nervous System Neoplasms with MCC) and MS-DRG 055 (Nervous System Neoplasms without 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 C79.31?

The CMS General Equivalence Mappings map C79.31 to ICD-9-CM 198.3.