Interstitial myositis, left forearm

This code signifies inflammation of the connective tissue within the muscles of the left forearm, specifically interstitial myositis. It indicates a non-suppurative inflammatory process affecting the muscle fibers and surrounding interstitial tissue in this anatomical location.

Assign this code when documentation clearly states interstitial myositis affecting the patient's left forearm. This diagnosis is typically supported by clinical examination findings of localized pain, swelling, and tenderness in the left forearm muscles, often confirmed by imaging studies (e.g., MRI) or muscle biopsy.

• Ensure the documentation specifies "interstitial" myositis and not another type of myositis (e.g., infective, toxic).
• Verify the laterality is explicitly stated as "left forearm" to avoid incorrect limb assignment.
• Do not confuse with M60.032 (Infective myositis, left forearm) or M60.232 (Granulomatous myositis, left forearm), which represent different etiologies of myositis.