Shoulder lesion in a 69 year old woman

Milwaukee shoulder syndrome (MSS) is a painful progressive arthropathy in which hydroxyapatite crystal deposition in synovial tissue induces lysosomal release of collagenase and neutral proteases. These enzymes are destructive to periarticular tissue, including the synovium, articular cartilage, rotator cuff muscles, and the intrasynovial cortical bone. MSS predominantly occurs in women (90%) over the age of 70 years of age with a clinical history marked by recurrent joint effusions and pain that classically worsens at night. Our patient is a 69 year old woman who presented with progressive shoulder pain, most prominent at night, with limited range of motion and swelling; intermittent discharge; and intermittent neck pain that radiated to her right upper extremity. Her medical history was notable for invasive carcinoma of the right breast treated with mastectomy and radiation. She was also treated with radiation therapy for right shoulder pain and a lucent right shoulder lesion presumed to be metastatic breast cancer. The remainder of her medical history consists of hypertension, diabetes mellitus, hyperlipidemia, and uneventful bilateral total knee arthroplasties. At presentation, she denied constitutional symptoms. Based on the patient’s history and physical examination, the differential diagnosis included primary and metastatic malignancy, radiation-induced sarcoma and necrosis, infection, Charcot disease, and crystal arthropathies. Physical examination, laboratory findings, and imaging studies led us to the diagnosis of MSS.