Uremic tumoral calcinosis in patients on peritoneal dialysis: Clinical, radiologic, and laboratory features

Background: Uremic tumoral calcinosis (UTC) has been analyzed in uremic patients on hemodialysis, but little is known about UTC in peritoneal dialysis (PD). In this study, we aimed to characterize UTC in uremic patients on PD. Methods: We retrospectively reviewed uremic patients on PD who developed UTC over a 9-year period. Clinical, radiologic, and laboratory features; treatments; and outcomes in those patients were assessed. One of the patients (case 7) is described as a case example. Results: The study enrolled 7 patients with a mean age of 41 years. Mean time from PD to UTC was 45.3 months. All patients were anuric but adequately dialyzed. Cardinal symptoms were local tenderness and limited range of joint motion. Lesions were mostly multifocal (n = 6) and predominantly involved shoulders, hands, feet, hips, and wrists. Metatarsophalangeal joint UTC was misdiagnosed as tophaceous gout in 2 patients. Main laboratory findings were hyperphosphatemia (7.9 ± 0.8 mg ²/dL ²), high Ca×P product [>65 mg ²/dL ² (range: 81.1 ± 11.5 mg2/dL2)], secondary hyperparathyroidism (SHPT) with various levels of intact parathyroid hormone (iPTH: 592.2 ± 315.2 pg/mL; <250 pg/mL in 2 patients). Medical treatments for UTC included P restriction, non-Ca-based phosphate binders, and adequate dialysis with low-Ca dialysate, but all treatments were ineffective. Parathyroidectomy (n = 3) can partially ameliorate UTC, but only 1 patient (case 7), who had extremely high iPTH (1085 pg/mL), manifested hungry bone syndrome (HBS) and had remarkable resolution of UTC. By contrast, in patients who underwent renal transplantation (n = 3), UTC completely resolved by about 1 year after surgery. Conclusions: Uremic tumoral calcinosis develops in anuric PD patients with uncontrolled hyperphosphatemia; it is usually multifocal, occurring around the weight-bearing joints or overused smaller joints. Aggressive medical therapy alone is ineffective, and parathyroidectomy appears to be unsatisfactory except in the presence of severe SHPT with postoperative HBS.