2026 ICD-10-CM Diagnosis Code M31.7Microscopic polyangiitis

ICD-10-CM Codes›M00–M99›M30-M36›M31

ICD-10-CM M31.7
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M31.7 is a billable ICD-10-CM diagnosis code for microscopic polyangiitis. 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 disorder of respiratory system due to microscopic polyangiitis. 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
M31.7
Billable Status
Yes — Valid for Submission
Code Describes
Microscopic polyangiitis
Short Description
Microscopic polyangiitis
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 CodeM31.7Microscopic polyangiitis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Disorder of respiratory system due to microscopic polyangiitis
  • Microscopic polyangiitis
  • Necrosis of artery
  • Polyarteritis
  • Vasculitis due to systemic disease

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Microscopic polyarteritis

Type 1 Excludes

  • polyarteritis nodosa M30.0

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.

    • Disorder(of)
      • glomerular (in)
        • microscopic polyangiitis
    • Glomerulonephritis
      • in (due to)
        • microscopic polyangiitis
    • Microscopic polyangiitis(polyarteritis)
    • Polyangiitis
      • microscopic
    • Polyarteritis
      • microscopic
    • Polyneuropathy(peripheral)
      • in (due to)
        • microscopic polyangiitis

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

  • Microscopic Polyangiitis

    a primary systemic vasculitis of small- and some medium-sized vessels. it is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (anca), and a paucity of immunoglobulin deposits in vessel walls.

Patient EducationClinical

Vasculitis

Vasculitis is an inflammation of the blood vessels. It happens when the body's immune system attacks the blood vessel by mistake. It can happen because of an infection, a medicine, or another disease. The cause is often unknown.

Read the full article at MedlinePlus

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

Convert M31.7 to ICD-9-CMHistory

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

ICD-9-CM
446.0 Polyarteritis nodosa
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 M31.7Overview

Is M31.7 (Other necrotizing vasculopathies) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report microscopic polyangiitis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M31.7 group to?

When microscopic polyangiitis 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 M31.7?

Under the General Equivalence Mappings, microscopic polyangiitis converts to ICD-9-CM 446.0 (polyarteritis nodosa). 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.