Juvenile rheumatoid arthritis with systemic onset, unsp knee

This code describes a form of juvenile idiopathic arthritis (JIA) characterized by systemic symptoms such as fever, rash, and lymphadenopathy, in addition to arthritis, specifically affecting an unspecified knee. It indicates a chronic inflammatory condition of unknown etiology presenting before 16 years of age.

Apply this code when documentation confirms a diagnosis of systemic-onset JIA with involvement of a knee, but the specific laterality (right or left) is not documented. This code is appropriate for initial and subsequent encounters for patients with this condition.

• Ensure documentation clearly specifies "systemic onset" and knee involvement.
• Avoid using this code if laterality of the affected knee is known; instead, use M08.261 (right) or M08.262 (left).
• Code any associated systemic manifestations (e.g., fever, rash) separately if they are significant and not considered integral to the JIA diagnosis.