Myositis ossificans progressiva, unspecified upper arm

This code describes a rare, progressive genetic disorder characterized by the formation of bone in muscles, tendons, ligaments, and other connective tissues, specifically affecting an unspecified upper arm. This heterotopic ossification leads to significant functional impairment and can cause joint immobility.

Use this code when documentation confirms a diagnosis of myositis ossificans progressiva with involvement of the upper arm, but without specifying laterality (left or right). This diagnosis is typically supported by genetic testing, imaging studies (X-rays, CT scans), and clinical examination revealing progressive heterotopic ossification.

• Ensure documentation clearly states "progressiva" to differentiate from myositis ossificans traumatica.
• Avoid using this code if laterality (left or right upper arm) is specified; use the more specific codes M61.121 or M61.122.
• Code any associated functional limitations or pain separately if documented.