Interstitial myositis, left thigh

This code signifies inflammation of the connective tissue within the muscles of the left thigh, specifically excluding infectious causes. It represents a non-suppurative inflammatory process affecting the interstitial spaces of the muscle fibers.

Apply this code when documentation clearly indicates interstitial myositis affecting the left thigh, often diagnosed via biopsy or advanced imaging. Supporting documentation should specify the non-infectious nature and the precise anatomical location.

• Ensure documentation differentiates interstitial myositis from other forms of myositis (e.g., infectious, polymyositis).
• Verify laterality (left thigh) is explicitly stated in the medical record.
• Do not use for generalized myositis without specific interstitial involvement or for myositis due to an underlying systemic disease, which would require an additional code.