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M06.1

Billable

Adult-onset Still's disease

HCC Category Mapping

V28HCC 93Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.175
V24HCC 40Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.307
ESRDHCC 40Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.000
RxHCCHCC 83Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
0.000

What This Code Means

A rare form of arthritis that begins in adulthood and includes fever, rash, and joint inflammation, often without the typical rheumatoid markers.

Coding Tips

  • This diagnosis requires documentation of systemic features including fever and characteristic rash in addition to arthritis
  • Confirm this is adult-onset (typically age 16 or older) to distinguish from juvenile-onset Still's disease

Clinical Significance

Adult-onset Still's disease is a rare systemic inflammatory disorder characterized by high spiking fevers, arthritis, and salmon-colored rash. This diagnosis indicates a complex multi-system disease requiring specialized rheumatologic care and immunosuppressive therapy.

Documentation Requirements

  • Clinical diagnosis of Adult-onset Still's disease by rheumatologist
  • Documentation of characteristic triad: fever, arthritis, and rash
  • Laboratory findings supporting diagnosis (elevated ferritin, ESR, CRP)
  • Exclusion of infectious, malignant, and other inflammatory conditions
  • Evidence of systemic manifestations (hepatomegaly, splenomegaly, lymphadenopathy)
  • Treatment history with corticosteroids, DMARDs, or biologics
  • Assessment of disease activity and organ involvement
  • Documentation of adult onset (not juvenile Still's disease)

Excludes 1 — Do NOT code together

  • Still's disease NOS (M08.2-)

Commonly Confused Codes

Code Hierarchy

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