A Case of Calcium Pyrophosphate Deposition Disease Involving a Lumbar Facet Joint Following Urinary Tract Infection.

A 75-year-old woman was admitted with urosepsis due to Escherichia coli infection. After improvement with a ureteral stent and antimicrobial agent, she complained of back pain and showed elevated inflammation marker levels. Arthralgia and arthritis of multiple peripheral joints were noted, and radiography indicated cartilage calcification. Magnetic resonance imaging revealed lumbar facet joint effusion. Her symptoms improved with nonsteroidal anti-inflammatory drug administration. Thus, she was diagnosed with calcium pyrophosphate deposition (CPPD)-related facet joint arthritis (FJA) rather than infectious FJA. CPPD-related FJA is an important differential diagnosis in elderly individuals with a risk of CPPD disease who complain of back pain.