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ICD-10-CM 2027

ICD-10 code for autoinflammatory syndrome

M04.9

Autoinflammatory syndrome, unspecified

✓ Billable / specific

From the official ICD-10-CM alphabetic index entry “Syndrome › autoinflammatory”. Page updated September 29, 2026.

About coding autoinflammatory syndrome

The ICD-10-CM code for autoinflammatory syndrome is M04.9 (Autoinflammatory syndrome, unspecified). The official index lists 1 more specific code, so check the documentation for details such as type, cause, site or severity before settling on M04.9.

Within M04, choose M04.9 (Autoinflammatory syndrome, unspecified) only when documentation doesn't support a more specific option: periodic fever syndromes (M04.1), Cryopyrin-associated periodic syndromes (M04.2), VEXAS syndrome (M04.3) and other autoinflammatory syndromes (M04.8).

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.

More specific autoinflammatory syndrome codes (official index)

  • specified type NEC M04.8 — Other autoinflammatory syndromes

Common questions about autoinflammatory syndrome ICD-10 codes

What is the ICD-10 code for autoinflammatory syndrome?

M04.9 — Autoinflammatory syndrome, unspecified. More specific codes apply when the documentation supports them: M04.8.

Is M04.9 billable?

Yes. M04.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can M04.9 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict M04.9 as a principal diagnosis.

Is M04.9 a CC or MCC?

No. M04.9 is neither a CC nor an MCC under MS-DRG v44.0.