Tophaceous pseudogout in a patient undergoing peritoneal dialysis.

Calcium pyrophosphate dihydrate deposition disease (pseudogout) is a crystal arthritis characterized by pyrophosphate dihydrate crystal deposition in the articular cartilage or synovium. In chronic kidney disease patients, the major causes of crystal arthritis are calcium oxalate crystals and basic calcium phosphate crystals. However, pseudogout is apparently infrequent among such patients. This report describes a rare case of tophaceous pseudogout (tumoral form of pseudogout) involving the hip joint in a peritoneal dialysis patient, as revealed by CT scan and synovial fluid aspiration. Fluid aspiration and oral NSAIDs improved the clinical symptoms. This report is the first to describe tophaceous pseudogout in a peritoneal dialysis patient, which suggests that pseudogout should be suspected in dialysis patients with unexplained arthritis.