[Calcium pyrophosphate dihydrate crystal deposition disease as an example of illness presentation in the elderly].

Illness presentation in the elderly may be entirely non-specific, with fatigue, loss of function or the presence of geriatric syndromes. We report a 90 years old male consulting in the emergency room for delirium that persisted throughout hospitalization without finding a cause. During the course of hospitalization mild fever appeared and a left knee swelling became apparent. A synovial fluid aspiration showed a leukocyte count of 360 per field with 60% polymorphonuclear cells. The culture was negative. With a presumptive diagnosis of pseudogout, cochicine and celecoxib were started with remission of the confusional state. The patient was discharged 13 days after admission in good conditions.