Myositis ossificans progressiva, unspecified finger(s)

This code signifies a rare genetic disorder characterized by progressive heterotopic ossification (bone formation in soft tissues) affecting the unspecified finger(s). It represents the advanced, chronic form of myositis ossificans where muscle and connective tissues are gradually replaced by bone, leading to severe functional impairment.

Apply this code when documentation explicitly states a diagnosis of myositis ossificans progressiva impacting an unspecified finger or fingers. This diagnosis is typically made based on clinical presentation, genetic testing (for ACVR1 mutation), and imaging studies confirming heterotopic ossification in the digits.

• Ensure documentation specifies "progressiva" to differentiate from localized myositis ossificans.
• Avoid using this code for traumatic myositis ossificans; those have distinct codes.
• If a specific finger is documented, use the more precise anatomical site code (e.g., M61.141 for right thumb).