Fever with acute arthritis in calcium pyrophosphate dihydrate deposition disease: A missed explanation for altered mental status in elderly patients?

Calcium pyrophosphate dihydrate (CPPD) deposition disease is a relatively c ommon condition primarily affecting the elderly. Various clinical presentat ions ranging from an acute arthritis resembling gout (pseudogout) to fever of unknown origin have been reported. We describe four elderly patients with fever and altered mental status. Eac h patient underwent an extensive unrevealing work-up. An acute arthritis mi ssed by the health-care team in their initial evaluation was later identifi ed, leading to rheumatologic consultation and subsequent diagnosis of CPPD disease after joint aspiration and synovial fluid analysis. Defervescence a nd resolution of mental status changes occurred after improvement of the ar thritis. Awareness that CPPD disease may present with systemic symptoms, including f ever and altered mental status, may assure careful examination of joints an d can prevent unnecessary testing and diagnostic delay.