Myositis ossificans progressiva, unspecified shoulder

This code represents myositis ossificans progressiva (fibrodysplasia ossificans progressiva, FOP) affecting an unspecified shoulder. FOP is a rare, severe genetic disorder characterized by progressive heterotopic ossification of soft tissues, leading to debilitating joint immobility. The "unspecified shoulder" indicates that the laterality (right or left) is not documented.

Use this code when documentation confirms a diagnosis of myositis ossificans progressiva and the affected anatomical site is the shoulder, but the specific side (left or right) is not specified. This diagnosis is typically made based on clinical presentation, genetic testing, and imaging studies showing heterotopic bone formation.

• Always strive for laterality. If documentation specifies right or left shoulder, use the more specific code (M61.111 or M61.112).
• This code should be a primary diagnosis when FOP is the reason for the encounter, or a secondary diagnosis when FOP is a comorbidity impacting treatment.
• Do not confuse with myositis ossificans traumatica (M61.0-), which is localized heterotopic ossification often following trauma, not the progressive genetic disorder.