2026 ICD-10-CM Diagnosis Code M04.1Periodic fever syndromes

ICD-10-CM Codes›M00–M99›M04›M04

ICD-10-CM M04.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M04.1 is a billable ICD-10-CM diagnosis code for periodic fever syndromes. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Autoinflammatory syndromes.

Code Identity

ICD-10-CM Code
M04.1
Billable Status
Yes — Valid for Submission
Code Describes
Periodic fever syndromes
Short Description
Periodic fever syndromes
Same as the full description in the CMS dataset.
Parent Code
M04
Autoinflammatory syndromes

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM04Autoinflammatory syndromes
CategoryM04Autoinflammatory syndromes
This CodeM04.1Periodic fever syndromes

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Amyloid of familial Mediterranean fever
  • Aphthous ulcer of mouth
  • Cervical lymphadenitis
  • Complex multigenic autoinflammatory syndrome
  • Congenital sideroblastic anemia, B-cell immunodeficiency, periodic fever, developmental delay syndrome
  • Deficiency of mevalonate kinase
  • Familial Mediterranean fever
  • Hemophagocytic lymphohistiocytosis
  • Hereditary periodic fever
  • Hyperimmunoglobulinemia D with periodic fever
  • Macrophage activation syndrome
  • Menstrual cycle dependent periodic fever
  • NLRC4-related familial cold autoinflammatory syndrome
  • NLRP12-associated hereditary periodic fever syndrome
  • Pericarditis due to familial Mediterranean fever
  • Periodic fever, infantile enterocolitis, autoinflammatory syndrome
  • PFAPA syndrome
  • Recurrent aphthous ulcer
  • Recurrent ulcer of mouth
  • Secondary systemic amyloidosis
  • TNF receptor-associated periodic fever syndrome

Tabular List NotesGuidance

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

Inclusion Terms

  • Familial Mediterranean fever
  • Hyperimmunoglobin D syndrome
  • Mevalonate kinase deficiency
  • Tumor necrosis factor receptor associated periodic syndrome TRAPS

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.

    • Arthritis, arthritic(acute) (chronic) (nonpyogenic) (subacute)
      • in (due to)
        • Mediterranean fever, familial
    • Deficiency, deficient
      • mevalonate kinase
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Mediterranean
        • familial
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • periodic (Mediterranean)
    • Mediterranean
      • fever
        • familial
    • Syndrome
      • hyperimmunoglobulin D
    • Syndrome
      • periodic fever
    • Syndrome
      • tumor necrosis factor receptor associated periodic (TRAPS)
    • TRAPS(tumor necrosis factor receptor associated periodic syndrome)

Clinical ClassificationClinical

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

CCSR MUS036
Autoinflammatory syndromes
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Familial Mediterranean Fever

    a group of hereditary autoinflammation diseases, characterized by recurrent fever, abdominal pain, headache, rash, pleurisy; and arthritis. orchitis; benign meningitis; and amyloidosis may also occur. homozygous or compound heterozygous mutations in marenostrin gene encoding pyrin result in autosomal recessive transmission; simple heterozygous, autosomal dominant form of the disease also exists with mutations in the same gene.

  • Macrophage Activation Syndrome

    a serious complication of childhood systemic inflammatory disorders that is thought to be caused by excessive activation and proliferation of t-lymphocytes and macrophages. it is seen predominantly in children with systemic onset juvenile idiopathic arthritis.

  • Cervical Lymphadenitis

    inflammation of the cervical lymph nodes.

Convert M04.1 to ICD-9-CMHistory

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

ICD-9-CM
277.31 Fam Mediterranean fever
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement M04.1 replaces the following previously assigned code(s):

  • E85.0 - Non-neuropathic heredofamilial amyloidosis
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M04.1Overview

Is M04.1 (Autoinflammatory syndromes) a billable code?

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

What MS-DRG does M04.1 group to?

When periodic fever syndromes 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 M04.1?

Under the General Equivalence Mappings, periodic fever syndromes converts to ICD-9-CM 277.31 (fam Mediterranean fever). 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.