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ICD-10-CM 2027 diagnosis code

M31.6Other giant cell arteritis

✓ Billable / specific

M31.6 is a valid, billable ICD-10-CM code for other giant cell arteritis. 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 M31.6

M31.6 is the ICD-10-CM diagnosis code for other giant cell arteritis. It belongs to category M31 (other necrotizing vasculopathies), block M30-M36 (systemic connective tissue disorders) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within M31, choose M31.6 (Other giant cell arteritis) only when documentation doesn't support a more specific option: hypersensitivity angiitis (M31.0), thrombotic microangiopathy (M31.1), Lethal midline granuloma (M31.2), Wegener's granulomatosis (M31.3), aortic arch syndrome [Takayasu] (M31.4), giant cell arteritis with polymyalgia rheumatica (M31.5), microscopic polyangiitis (M31.7), other specified necrotizing vasculopathies (M31.8) and 1 more.

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 545 (Connective Tissue Disorders with MCC, relative weight 2.3892), DRG 546 (Connective Tissue Disorders with CC, relative weight 1.1745) and DRG 547 (Connective Tissue Disorders without CC/MCC, relative weight 0.7526), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), 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 446.5 (giant cell arteritis).

Notes that apply from higher levels

Instructions written at a parent level also apply to M31.6.

Broader instructions also apply from M30-M36 Systemic connective tissue disorders and Chapter 13: Diseases of the musculoskeletal system and connective tissue.

Alphabetic index entries

4 entries

Terms in the official ICD-10-CM index that lead to M31.6.

Codes whose notes reference M31.6

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 →
  • 446.5Giant cell arteritisapproximate

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 M31.6

Is M31.6 billable?

Yes. M31.6 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can M31.6 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict M31.6 as a principal diagnosis.

Is M31.6 a CC or MCC?

No. M31.6 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does M31.6 group to?

M31.6 is used in the MS-DRG v44.0 logic for MS-DRG 545 (Connective Tissue Disorders with MCC), MS-DRG 546 (Connective Tissue Disorders with CC) and MS-DRG 547 (Connective Tissue Disorders 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 M31.6?

The CMS General Equivalence Mappings map M31.6 to ICD-9-CM 446.5.