Adult-onset Still's disease

This code identifies a rare, systemic inflammatory disorder characterized by high fevers, evanescent rash, arthralgia/arthritis, and other systemic manifestations such as lymphadenopathy, hepatosplenomegaly, and serositis. It is a diagnosis of exclusion, typically affecting young adults, and can lead to significant morbidity if not promptly recognized and managed.

Assign this code for patients diagnosed with Adult-onset Still's disease, confirmed by clinical criteria and exclusion of other inflammatory conditions. Documentation should clearly indicate the adult presentation of Still's disease, distinguishing it from juvenile idiopathic arthritis. This code is appropriate when the physician explicitly states "Adult-onset Still's disease."

• Do not use this code if the documentation simply states "Still's disease" without specifying "adult-onset"; in such cases, refer to the Excludes1 note.
• Ensure the patient's age at onset aligns with the "adult-onset" classification to avoid miscoding with juvenile forms.
• Code associated manifestations (e.g., arthritis, pericarditis) separately as secondary diagnoses.