Case Presentation: A 41 year-old female with a history significant for end stage renal disease (ESRD) secondary to focal segmental glomerulosclerosis (FSGS) on peritoneal dialysis for two years, uremic pericardial effusion with pericardiocentesis three years prior, and polyarticular gout on allopurinol presented as a transfer from an outside hospital for evaluation due to concerns for recurrent pericarditis. She presented initially with severe right shoulder pain with radiation to her neck, pleuritic chest pain, and jaw pain associated with headache. The patient recently was found to have transverse process fracture of L1-L4 requiring no surgical intervention after a mechanical fall. Although she endorsed diffuse myalgias and polyarthralgias ongoing for weeks, the recent fall exacerbated her pain, especially in the right shoulder radiating into her neck. The pain was exacerbated by any movement and she was unable to actively abduct her right arm. She stated the shoulder was sore after the fall but denied any direct trauma. Rheumatology recommended MRI of her shoulder which showed findings consistent with hydroxyapatite deposition disease involving the distal clavicle with evidence of chronic erosion and soft tissue edema. Dedicated shoulder radiographs demonstrated right clavicular erosion with increased calcium deposition and multifocal areas of soft tissue calcification in the supraspinatus and subscapularis tendons. She was initiated on intravenous steroids and transitioned to an oral steroid taper with eventual improvement in her pain.

Discussion: Milwaukee shoulder syndrome (MSS) or calcific tendonitis is a chronic shoulder syndrome of shoulder arthritis, which presents with chronic shoulder pain and loss of function. It is characterized by deposition of calcium hydroxyapatite in the affected tendon, most commonly the supraspinatus, but can occur in all tendons of the rotator cuff and sometimes causes destructive erosion of associated bones. Deposits can be spontaneously resorbed, but healing of tendons usually occurs with supportive care and time. Calcific tendinitis presenting with radiographic evidence of bone erosion has been reported only a handful of times in literature. In the largest reported case series, which involved 30 patients, 80 percent were women; the mean age was 72 years, ranging from 50 to 90 years of age. This patient may be one of the youngest women with this condition ever reported. ESRD likely played a large role in this rare presentation. There are even fewer reports of calcific tendonitis occurring in the setting of ESRD. This is significant as change in management can occur. Calcific arthritis in the setting of ESRD is managed by reducing calcium and phosphate levels. If traditional therapies fail, systemic administration of sodium thiosulfate may be useful in this setting based on some case reports.

Conclusions: Milwaukee shoulder syndrome is a rare destructive calcium phosphate crystalline arthropathy of unknown etiology. It is a noninflammatory condition caused by calcium hydroxyapatite crystals in the synovial fluid and most commonly seen in elderly women. We describe a younger female patient who presented with severe shoulder pain and found to have MSS in the setting of ESRD.

IMAGE 1: Multifocal calcific foci are identified around shoulder with localized calcific foci noted adjacent to the distal clavicle with erosions of the distal clavicle.

IMAGE 2: Findings most consistent with hydroxyapatite deposition disease (calcific tendinitis) involving the distal clavicle with associated chronic erosion and adjacent soft tissue and bone marrow edema