Other ossification of muscle, other site

This code signifies the pathological formation of bone tissue within muscle at an anatomical location not specifically classified elsewhere. This condition, known as heterotopic ossification or myositis ossificans, involves the abnormal deposition of lamellar bone in soft tissues where bone does not normally exist. It can lead to pain, swelling, and restricted range of motion.

Use this code when documentation specifies heterotopic ossification or myositis ossificans affecting a muscle in a site other than the hip, thigh, or upper arm. This diagnosis is typically supported by imaging studies (e.g., X-ray, CT scan) confirming the presence of bone within muscle tissue, along with clinical notes detailing the affected "other" site.

• Ensure the documentation clearly specifies the affected muscle and confirms it's not the hip, thigh, or upper arm.
• Distinguish from calcification of muscle (M61.4-), which involves calcium deposits rather than true bone formation.
• Code any underlying cause or associated trauma if documented and clinically relevant.