Hydroxyapatite deposition disease, unspecified site

This code represents a form of crystal deposition arthropathy characterized by the accumulation of hydroxyapatite crystals within periarticular soft tissues, such as tendons, ligaments, and joint capsules. It typically manifests as acute, severe pain and inflammation, often mimicking other inflammatory conditions.

Use this code when the medical record documents a diagnosis of hydroxyapatite deposition disease, but the specific anatomical site affected is not specified. This diagnosis is often supported by imaging studies (e.g., radiography showing calcifications) and clinical presentation consistent with crystal-induced inflammation.

• Only use this code when the site is truly unspecified; otherwise, code to the specific anatomical location (e.g., shoulder, knee).
• Differentiate from other crystal arthropathies like gout (urate crystals) or pseudogout (calcium pyrophosphate dihydrate crystals).
• Ensure documentation clearly states "hydroxyapatite deposition disease" or "HADD."