Characterized by large, extra-articular soft tissue calcifications involving mainly the hips, shoulders, and elbows.
Lesions are lobulated, firm, slow-growing, nontender and may have associated draining ulcerations.
These lobulated masses originate from the joint the bursa and may compress nearby neurovascular structures.
UTC occurs up to approximately 7% of patients receiving hemodialysis.
Mitral valve calcification will develop in 50% of patients with ESRD.
Polypoid calcification deposits occur in the anterior and posterior leaflet bases, sparing the free edges and chordae tendinae.
UTC may be associated with annular calcifications of the mitral valve with stenosis or regurgitation.
UTC differential diagnosis of soft issue calcification includes: myosotis ossificans, sarcomas, heterotropic ossification, sarcoidosis, and scleroderma.
Polypoid drainage sites may appear milky, containing calcium carbonate, calcium phosphate, calcium hydroxyapatite, and calcium oxalate.
Similar events may occur with crystalline arthropathies, infectious arthritis and soft tissue abscesses.
On evaluation of aspirated sites, microscopy reveals whitish yellow, pasty material that is amorphous and may contain psammoma bodies like masses that are variably birefringent, and staining with alizarin S red that may identify these calcific bodies.
Pathogenesis suggested that when the product of serum concentrations of calcium and phosphate exceeds 65-75 mg/dL calcium salts precipitate.
Secondary hyperparathyroidism and abnormal vitamin D metabolism in ESRD increases calcium and phosphate release from bones into the blood and decrease urinary phosphate excretion.
Treatment is to decrease the concentrations f calcium and phosphate products by low calcium dialysate, use of non-calcium containing phosphate binders, calcimimetics, vitamin d, and bisphosphonates.
Parathyroidectomy may be indicated.
Renal transplantation may be beneficial.
Surgical resection of calcification masses may be beneficial.