ICD-10 Code M04 – Autoinflammatory syndromes (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code M04 – Autoinflammatory syndromes
What it is
M04 identifies autoinflammatory syndromes, a group of disorders marked by recurrent inflammation without a clear autoimmune cause. Use it when the record documents this diagnosis or a closely related autoinflammatory condition.
Clinical signs
Clinical features vary; refer to documentation. Commonly noted findings include recurrent fever, inflammatory flares, rash, joint pain, and other signs of systemic inflammation.
When to use this code
Use M04 when the provider documents an autoinflammatory syndrome as the confirmed diagnosis. It may also apply when notes describe a specific syndrome within this category and no more specific ICD-10-CM code is available. Check the chart for the exact named condition.
Do not use for
Do not use this code for autoimmune diseases, isolated fever workups, or nonspecific inflammatory symptoms without a documented autoinflammatory syndrome. If the diagnosis is uncertain, check documentation.
Coding tip
Assign the most specific autoinflammatory diagnosis documented, and verify whether the record names a subtype that requires a different code.