Pseudogout in 3 patients with presumed therapy-resistant rheumatoid arthritis

3 patients, 2 women aged 71 and 76 and a 55-year-old man, were originally diagnosed with rheumatoid arthritis (RA) and treated with disease-modifying antirheumatic drugs (DMARDs); two of these patients fulfilled the American College of Rheumatology criteria for RA. Because the symptoms persisted, the diagnosis was reconsidered. It turned out that they had pseudogout, which is an arthropathy caused by the deposition of calcium pyrophosphate crystals; the younger woman had no obvious metabolic disorder, the older woman had underlying hyperparathyroidism, and in the man the arthropathy was probably due to benign hypercalcaemia. DMARDs were replaced by NSAIDs. Varying degrees ofarthropathy persisted in the women, but in the man they were clearly decreased. In addition to resembling gout, the clinical manifestations of pseudogout can also mimic RA. It is important to distinguish pseudogout from RA because their treatment is completely different. Furthermore, pseudogout can be the first or sole symptom of a metabolic disorder.