Uremic tumoral calcinosis in hemodialysis patients: Clinicopatholological findings and identification of calcific deposits

Objective. Extraskeletal calcifications generally develop in uremic patients. Periarticular massive calcifications, referred to as uremic tumoral calcinosis (UTC), represent solitary or multifocal calcium phosphate deposits. Our objectives were to clinically analyze a series of 8 patients with UTC undergoing hemodialysis, and to characterize calcium deposits in UTC. Methods. The clinical, radiological, and pathological features of 8 consecutive patients (4 men and 4 women, mean age 49 yrs) with UTC were analyzed, and treatment and outcome were evaluated. Calcitic specimens from the 8 patients were analyzed by x-ray diffraction, Raman spectroscopy, and infrared spectroscopy. Results. Unifocal UTC was observed in 5 patients, whereas multifocal lesions occurred in 3 patients. The most common sites of UTC were the shoulders, elbows, and hands. Elevated serum calcium and phosphorus and intact parathyroid hormone were detected in 63% (n = 5), 100% (n = 8), and 63% (n = 5) of the patients, respectively. An increased calcium-phosphorus (CaxP) product was observed in 6 patients. Medical intervention to decrease the CaxP product achieved complete remission in 3 of 5 patients with solitary UTC, whereas this treatment was ineffective for multiple UTC. The 8 calcium deposits were identified as carbonate apatite. Conclusion. The most important pathogenic factors in UTC are an increased CaxP product and hyperphosphoremia, which is not necessarily related to hyperparathyroidism. Medical intervention is effective for solitary UTC, but combined treatment (surgery and medical therapy) is required for multiple UTC. Calcium deposits in UTC are composed of carbonate apatite.