2026 ICD-10-CM Diagnosis Code M31.5Giant cell arteritis with polymyalgia rheumatica

ICD-10-CM Codes›M00–M99›M30-M36›M31

ICD-10-CM M31.5
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M31.5 is a billable ICD-10-CM diagnosis code for giant cell arteritis with polymyalgia rheumatica. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 545 through 547. Coders also document this condition as giant cell arteritis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Systemic lupus erythematosus and connective tissue disorders and Vasculitis.

Code Identity

ICD-10-CM Code
M31.5
Billable Status
Yes — Valid for Submission
Code Describes
Giant cell arteritis with polymyalgia rheumatica
Short Description
Giant cell arteritis with polymyalgia rheumatica
Same as the full description in the CMS dataset.
Parent Code
M31
Other necrotizing vasculopathies

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM30-M36Systemic connective tissue disorders
CategoryM31Other necrotizing vasculopathies
This CodeM31.5Giant cell arteritis with polymyalgia rheumatica

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Giant cell arteritis
  • Giant cell arteritis with polymyalgia rheumatica
  • Polymyalgia rheumatica

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Arteritis
      • giant cell NEC
        • with polymyalgia rheumatica
    • Polymyalgia
      • arteritica, giant cell
    • Polymyalgia
      • rheumatica
        • with giant cell arteritis

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS024
Systemic lupus erythematosus and connective tissue disorders
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR CIR037
Vasculitis
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Giant Cell Arteritis

    a systemic autoimmune disorder that typically affects medium and large arteries, usually leading to occlusive granulomatous vasculitis with transmural infiltrate containing multinucleated giant cells. the temporal artery is commonly involved. this disorder appears primarily in people over the age of 50. symptoms include fever; fatigue; headache; visual impairment; pain in the jaw and tongue; and aggravation of pain by cold temperatures. (from adams et al., principles of neurology, 6th ed)

  • Polymyalgia Rheumatica

    a syndrome in the elderly characterized by proximal joint and muscle pain, high erythrocyte sedimentation rate, and a self-limiting course. pain is usually accompanied by evidence of an inflammatory reaction. women are affected twice as commonly as men and caucasians more frequently than other groups. the condition is frequently associated with giant cell arteritis and some theories pose the possibility that the two diseases arise from a single etiology or even that they are the same entity.

Patient EducationClinical

Giant Cell Arteritis

Giant cell arteritis is a disorder that causes inflammation of your arteries, usually in the scalp, neck, and arms. It narrows the arteries, which keeps blood from flowing well. Giant cell arteritis often occurs with another disorder called polymyalgia rheumatica. Both are more common in women than in men.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M31.5 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
446.5 Giant cell arteritis
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M31.5Overview

Is M31.5 (Other necrotizing vasculopathies) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report giant cell arteritis with polymyalgia rheumatica on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M31.5 group to?

When giant cell arteritis with polymyalgia rheumatica is the principal diagnosis on an inpatient stay, it groups to MS-DRG 545, 546, 547, with relative weights from 0.8362 to 2.4817 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M31.5?

Under the General Equivalence Mappings, giant cell arteritis with polymyalgia rheumatica converts to ICD-9-CM 446.5 (giant cell arteritis). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.