Pseudogout in ochronosis. Report of a case.

Calcium pyrophosphate dihydrate crystals were identified in synovial fluid white blood cells during an episode of acute arthritis in a patient with ochronosis and chondrocalcinosis. Review of the histories and radiographs of 5 other patients with ochronosis demonstrated two additional instances of chondrocalcinosis. Both of these patients had episodes of arthritis consistent with pseudogout. This suggests that pseudogout, which has been found in increased incidence in some metabolic diseases, may also be more common in ochronosis.