New-onset of polymyalgia rheumatica in an elderly patient with calcium pyrophosphate deposition (CPPD) disease.

We herein present an 87-year-old febrile female patient with knee joint pain. The presence of calcium pyrophosphate crystals in synovial fluids led to a diagnosis of calcium pyrophosphate dihydrate (CPPD) disease. She was treated with nonsteroidal anti-inflammatory drugs (NSAIDs), resulting in the resolution of the knee joint arthritis and inflammatory signs. However, 3 weeks from the first onset of knee joint pain, she relapsed with febrile episodes accompanied by myalgia around the shoulder and morning stiffness. Ultrasonography revealed bilateral long head biceps tenosynovitis. A diagnosis of polymyalgia rheumatica (PMR), considered to be a complication in addition to the pre-existing CPPD disease, was made according to the EULAR/ACR provisional classification criteria for PMR. Steroid therapy resolved the symptoms. This case demonstrates the importance of considering the possibility of overlapping PMR in patients with an atypical clinical course of CPPD disease. Careful differentiation of PMR and CPPD disease is necessary in elderly patients with atypical inflammatory arthropathy.