M04.9 — Autoinflammatory syndrome, unspecified
Is M04.9 billable?
Yes, but M04.9 is an unspecified code. M04.9 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, M04.9 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting M04.9 — the more specific alternatives are listed below.
M04.9 at a glance
| Code | M04.9 |
|---|---|
| Description | Autoinflammatory syndrome, unspecified |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does M04.9 group to?
M04.9 sits in MDC 08 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 545Connective Tissue Disorders with MCCmedical
- 546Connective Tissue Disorders with CCmedical
- 547Connective Tissue Disorders without CC/MCCmedical
How is M04.9 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to M04.9. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Disease, diseased › autoinflammatory
- Syndrome › autoinflammatory
Excludes2 — not included here — inherited from Chapter 13
The conditions below are not part of M04.9, but a patient may have both at the same time. When documentation supports it, M04.9 and the excluded code may both be reported.
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Excludes2 — not included here — inherited from M04
The conditions below are not part of M04.9, but a patient may have both at the same time. When documentation supports it, M04.9 and the excluded code may both be reported.
- Crohn's disease (K50.-)
How long has M04.9 existed?
M04.9 first appears in FY2018 (FY2017 is not available, so it may have appeared then).
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.