ICD-10 Code M30.1: Polyarteritis with lung involvement (EGPA)

Key Takeaways

ICD-10 Code M30.1 is a fully billable diagnosis code for Polyarteritis with Lung Involvement, covering both Churg-Strauss syndrome and its current preferred name, Eosinophilic Granulomatosis with Polyangiitis (EGPA).

Two official inclusion terms apply: Allergic granulomatous angiitis and Eosinophilic granulomatosis with polyangiitis [EGPA]. Either diagnosis supports M30.1 as the correct code.

Microscopic polyarteritis (M31.7) carries a Type 1 Excludes relationship with the M30 parent, meaning M31.7 must never be coded at the same visit as M30.1.

Pabau’s claims management software supports accurate vasculitis coding workflows by structuring documentation, tracking code pairings, and flagging exclusion conflicts before claims are submitted.

ICD-10 Code M30.1: Definition and clinical overview

Rare autoimmune vasculitis conditions are among the most under-documented diagnoses in clinical practice, and incorrect coding leads to denied claims, audit exposure, and gaps in population health tracking. Situational anxiety ICD-10 coding presents similar challenges for coders navigating overlapping diagnostic criteria, but M30.1 adds a further layer of complexity because the condition itself has been renamed since the code was first established.

ICD-10 Code M30.1 is the billable diagnosis code for Polyarteritis with Lung Involvement, currently valid for FY2026 HIPAA-covered transactions. The condition it describes – once called Churg-Strauss syndrome – is now formally classified by most rheumatology bodies as Eosinophilic Granulomatosis with Polyangiitis (EGPA). Importantly, both names are clinically valid; both are captured under M30.1.

This guide covers billable status, inclusion terms, the M30 code family, exclusion rules, ICD-9-CM crosswalk, documentation requirements, and practical billing guidance for providers managing EGPA and related vasculitis diagnoses.

Billable status and ICD-10 Code M30.1 code hierarchy

M30.1 is a billable/specific diagnosis code. Specifically, it provides the required level of specificity for HIPAA-covered electronic transactions and is valid for the current fiscal year (FY2026, October 1, 2025 through September 30, 2026). Therefore, using the parent code M30 alone is not acceptable for billing: ICD List confirms M30 is a non-billable header code, and payers require the four-character specificity of M30.1 on claims.

Furthermore, the M30 block falls under the broader M30-M36 range of systemic connective tissue disorders, alongside M31 (Other necrotizing vasculopathies), M32 (Systemic lupus erythematosus), M33 (Dermatopolymyositis), M34 (Systemic sclerosis), M35 (Other systemic involvement of connective tissue), and M36 (Systemic disorders in diseases classified elsewhere).

Inclusion terms and EGPA terminology for ICD-10 Code M30.1

The ICD-10-CM tabular list recognises two official inclusion terms under M30.1:

• Allergic granulomatous angiitis
• Eosinophilic granulomatosis with polyangiitis [EGPA]

Notably, the naming history matters for coders and clinicians alike. Jacob Churg and Lotte Strauss first described the condition in 1951, and “Churg-Strauss syndrome” remained the standard term for decades. In 2012, the American College of Rheumatology (ACR) and the European Alliance of Associations for Rheumatology adopted EGPA as the preferred naming, reflecting the condition’s clinical hallmarks: eosinophilia, granulomatous inflammation, and ANCA-associated small-vessel vasculitis with predominant lung involvement.

In clinical practice, rheumatology referral letters, pulmonology notes, and discharge summaries may use any of the three terms (Churg-Strauss, EGPA, allergic granulomatous angiitis). Therefore, all three map correctly to M30.1. Consequently, coders encountering any of these terms in the medical record should default to M30.1 without seeking further clarification from the provider, as all are official inclusion terms under the same code. For practices managing complex autoimmune conditions, integrative medicine practice software that supports structured diagnostic documentation helps teams capture the correct clinical terminology at intake.

Clinical profile of EGPA/Churg-Strauss

Clinically, EGPA is a rare ANCA-associated vasculitis affecting small and medium-sized vessels. The condition typically presents in three phases: a prodromal asthma and atopy phase (often lasting years), a blood and tissue eosinophilia phase, and a vasculitic phase involving multiple organs. Notably, lung involvement is the defining feature, with asthma present in almost all cases.

Anti-neutrophil cytoplasmic antibody (ANCA) positivity, particularly perinuclear ANCA (p-ANCA/MPO-ANCA), appears in approximately 40% of EGPA patients and tends to correlate with renal and nerve involvement. Additionally, providers should document ANCA status explicitly in clinical notes, as payers increasingly request serological evidence when reviewing claims for rare vasculitis diagnoses.

ICD-10 Code M30.1 vs related vasculitis codes: coding distinctions

Vasculitis coding requires precise distinction between conditions that share clinical features. Three codes cause the most confusion alongside M30.1:

In particular, the distinction between M30.0 and M30.1 is clinically significant and coding-critical. Polyarteritis nodosa (M30.0) involves medium-sized vessels without the eosinophilic or granulomatous features of EGPA, and it does not involve pulmonary vasculitis as a defining characteristic. Therefore, if the provider’s diagnosis specifically references lung involvement alongside granulomatous or eosinophilic pathology, M30.1 is correct. Without that specificity, M30.0 may be more appropriate, and a query to the provider is warranted rather than an assumption.

For coders handling complex vasculitis cases, the AAPC Codify ICD-10-CM lookup provides detailed tabular notes including excludes relationships and crosswalk data alongside each code record.

Type 1 Excludes: M31.7 microscopic polyarteritis

The M30 parent code carries a Type 1 Excludes note for microscopic polyarteritis (M31.7). A Type 1 Excludes indicates that the two conditions cannot coexist: they represent mutually exclusive diagnoses at the clinical level. Specifically, microscopic polyarteritis involves pure small-vessel disease without eosinophilia or asthma, which is definitionally incompatible with EGPA/Churg-Strauss. As a result, coding M30.1 and M31.7 on the same claim will trigger an edit, and payers will deny or query the claim.

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Documentation requirements for ICD-10 Code M30.1

EGPA is a rare condition, and payers routinely scrutinise claims for uncommon autoimmune vasculitis diagnoses. Therefore, strong clinical documentation is the first line of defence against audit queries and denial. Structured patient records make it significantly easier to surface the specific clinical evidence payers look for when reviewing M30.1 claims.

The following documentation elements support the M30.1 diagnosis and reduce payer friction:

• Confirmed or suspected EGPA diagnosis from a rheumatologist, pulmonologist, or treating internist, with explicit reference to either Churg-Strauss, EGPA, or allergic granulomatous angiitis
• History of asthma or atopic disease, including duration and severity, as the prodromal asthma phase is a defining clinical feature
• Peripheral eosinophil count, ideally with documented threshold (typically exceeding 10% or greater than 1.5 x 10^9/L)
• Evidence of lung involvement: chest imaging (CT thorax), pulmonary function tests, or biopsy confirming pulmonary vasculitis or eosinophilic infiltrates
• ANCA serology results (MPO-ANCA/p-ANCA), with positive or negative status documented; negative ANCA does not exclude EGPA
• Multi-organ involvement documentation: peripheral neuropathy, renal involvement, skin lesions, or cardiac findings strengthen the vasculitis diagnosis
• Histopathology report when tissue biopsy was performed, particularly noting eosinophilic infiltration, granulomata, or vasculitis

For practices using digital clinical forms, pre-consultation templates can be structured to prompt collection of eosinophil counts, ANCA results, and imaging references at the point of care, reducing the need for retrospective documentation queries. The ICD-10 coding for autoimmune and neurological conditions follows similar documentation logic: specificity in the clinical record is what separates a clean claim from an audit trigger.

Payer-specific considerations

Some payers require laboratory or biopsy confirmation before approving coverage for rare vasculitis diagnoses. While ICD-10-CM official guidelines do not mandate specific test results for M30.1, individual payer policies may impose additional requirements. Providers should check local coverage determinations (LCDs) for their Medicare Administrative Contractor (MAC) and review commercial plan policies before submitting claims for high-cost biologics or specialty infusions associated with EGPA treatment. Using HIPAA-compliant clinic documentation workflows ensures that supporting evidence is stored, retrievable, and shareable when payers request records.

ICD-9-CM crosswalk and historical context for M30.1

Before ICD-10-CM replaced ICD-9-CM for US healthcare transactions in October 2015, Churg-Strauss syndrome was coded under ICD-9-CM 446.4 (Wegener’s granulomatosis). However, this is an approximate crosswalk only. ICD-9-CM 446.4 grouped several forms of granulomatous vasculitis together, including Wegener’s (now granulomatosis with polyangiitis) and Churg-Strauss under a single code. Consequently, the ICD-10-CM transition brought precision: M30.1 is now specific to EGPA/Churg-Strauss alone, while granulomatosis with polyangiitis moved to M31.3.

Similarly, practices conducting retrospective data analysis or translating historical claims for research or audit purposes should treat any 446.4 crosswalk to M30.1 as approximate. As a result, the original ICD-9-CM record should be reviewed for clinical narrative to confirm whether the intended diagnosis was Churg-Strauss/EGPA rather than Wegener’s granulomatosis before assigning M30.1 in a converted dataset. For bidirectional crosswalk tools, ICD-10 codes for intracranial vascular conditions illustrate similar crosswalk precision challenges where one ICD-9 code maps to multiple ICD-10 codes depending on clinical specificity.

Coding guidelines and billing implications for M30.1

M30.1 follows the standard sequencing rules for principal versus secondary diagnosis coding under the ICD-10-CM Official Guidelines for Coding and Reporting. For example, in an inpatient setting, M30.1 may be sequenced as the principal diagnosis when EGPA is the condition established to be chiefly responsible for the admission. In outpatient and office settings, M30.1 should reflect the confirmed or working diagnosis documented in the provider’s assessment.

Key coding guidance points:

• Combination coding: M30.1 does not have combination codes for specific organ manifestations. Coders should assign the appropriate ICD-10-CM codes additionally for complications such as peripheral neuropathy, glomerulonephritis, or heart failure.
• Asthma coding: Asthma in EGPA is a clinical feature of the underlying disease, not an independent comorbidity in most coding contexts. Providers and coders should follow clinical guidelines and any applicable Coding Clinic advice before assigning asthma separately alongside M30.1.
• ANCA-associated vasculitis: ICD-10-CM does not provide a specific ANCA designation within M30.1. ANCA-positivity is a laboratory qualifier, not a separate code assignment.
• Active vs. remission status: ICD-10-CM does not include remission subcategories under M30.1. Additionally, document active disease status in clinical notes and code M30.1 for active visits; follow facility policy for surveillance visits where the condition is in remission.

Practices managing autoimmune vasculitis billing benefit from claims management software that tracks excluded code pairings and flags M30.1 claims for CDI review automatically. For practices needing robust audit trail capabilities, compliance management tools help ensure documentation standards are met across the care team before submission. The CMS ICD-10 codes and guidelines page is the authoritative reference for FY2026 official guidelines and any mid-year updates.

Conclusion

Rare vasculitis diagnoses like EGPA/Churg-Strauss deserve the same documentation rigour as any high-volume condition. In summary, M30.1 is billable, specific, and covers all three clinical names for the condition, but it sits within a closely related family of vasculitis codes where precision matters. The Type 1 Excludes rule for M31.7 is an absolute constraint, and the approximate ICD-9 crosswalk from 446.4 demands clinical verification before retrospective data conversion.

For practices treating complex autoimmune conditions, Pabau’s practice management software brings together structured clinical documentation, automated claim workflows, and compliance tracking in a single platform. Book a demo to see how Pabau supports accurate ICD-10 coding from the consultation room to the payer.

Continue your research

Need guidance on related vascular ICD-10 codes? ICD-10 codes for intracranial vascular conditions provides a detailed reference for coders managing complex vascular diagnosis hierarchies.

Looking to improve patient documentation workflows? Patient care management for rare conditions covers how to structure long-term records for complex autoimmune diagnoses.

Managing HIPAA compliance across your coding team? Healthcare CRM workflows explains how integrated platforms reduce compliance risk in multi-provider environments.

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