Shoulder arthropathy has a broad musculoskeletal differential diagnosis, but glenohumeral joint destruction with rotator cuff damage should raise suspicion for Milwaukee shoulder syndrome (MSS). MSS is a basic calcium phosphate (BCP) crystal–associated arthropathy characterized by large, often hemorrhagic, but minimally inflammatory joint effusions. BCP crystals, such as hydroxyapatite, are not birefringent under polarized light and require special staining (e.g., alizarin red) for detection in synovial fluid. Although MSS characteristically affects older women, this case highlights other associations, including joint overuse.
Comment
Shoulder arthropathy has a broad musculoskeletal differential diagnosis, but glenohumeral joint destruction with rotator cuff damage should raise suspicion for Milwaukee shoulder syndrome (MSS). MSS is a basic calcium phosphate (BCP) crystal–associated arthropathy characterized by large, often hemorrhagic, but minimally inflammatory joint effusions. BCP crystals, such as hydroxyapatite, are not birefringent under polarized light and require special staining (e.g., alizarin red) for detection in synovial fluid. Although MSS characteristically affects older women, this case highlights other associations, including joint overuse.