2026 ICD-10-CM Diagnosis Code M31.0Hypersensitivity angiitis
ICD-10-CM Codes›M00–M99›M30-M36›M31
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 93
- Chronic Condition
M31.0 is a billable ICD-10-CM diagnosis code for hypersensitivity angiitis. 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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 77 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Systemic lupus erythematosus and connective tissue disorders and Vasculitis.
For Medicare Advantage risk adjustment, M31.0 maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders) under the V28 model, adding a risk factor of about 0.617 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
M31.0 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Anti-glomerular basement membrane disease
- Cutaneous leukocytoclastic angiitis
- Goodpasture's syndrome
- Hypersensitivity angiitis
- Hypersensitivity reaction mediated by immune complex
- Infantile acute hemorrhagic edema
- Necrotizing cutaneous vasculitis
- Normocomplementemic urticarial vasculitis
- Pulmonary renal syndrome
- Single organ vasculitis
- Urticarial vasculitis
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Goodpasture's syndrome
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
hypersensitivity M31.0
Disease, diseased See Also: Syndrome;
Disorder (of) See Also: Disease;
Glomerulonephritis See Also: Nephritis; N05.9
Goodpasture's syndrome M31.0
Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic) N05.9
Syndrome See Also: Disease;
leukocytoclastic M31.0
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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 M31.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M31.0Overview
What is the ICD-10 code for hypersensitivity angiitis?
The ICD-10-CM code for hypersensitivity angiitis is M31.0 (sometimes written as M310). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is M31.0 (Other necrotizing vasculopathies) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report hypersensitivity angiitis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does M31.0 group to?
When hypersensitivity angiitis 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.
Is M31.0 a CC or MCC?
CMS lists M31.0 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 77 closely related codes in its exclusion list.
What is the ICD-9 equivalent of M31.0?
Under the General Equivalence Mappings, hypersensitivity angiitis converts to ICD-9-CM 446.20 (hypersensit angiitis NOS), 446.21 (Goodpasture's syndrome), and 446.29 (hypersensit angiitis NEC). The mapping is approximate, so confirm the match fits the documentation.
What HCC is M31.0?
M31.0 (hypersensitivity angiitis) maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders), commonly written as HCC 93, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 40 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 84.
Does M31.0 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M31.0 adds a risk adjustment factor of about 0.617 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.288 to 0.617 depending on the payment segment). HCC 93 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 93 category page.
