Which investigations should be performed to confirm a diagnosis of calcium pyrophosphate deposition disease (CPPD) in a suspected case?

To confirm a diagnosis of calcium pyrophosphate deposition disease (CPPD) in a suspected case, the definitive investigation involves the identification of calcium pyrophosphate crystals [1, Tsui 2012]. This is typically achieved through the microscopic examination of synovial fluid obtained from an affected joint NICE NG219. The identification of specific crystals in synovial fluid is a cornerstone for definitively diagnosing crystal arthropathies, similar to how urate crystals confirm gout NICE NG219,NICE CKS. The presence of these crystals is fundamental to understanding the mechanisms of crystal deposition in CPPD and is a key aspect in its nomenclature and classification [1, Tsui 2012, Tedeschi 2019].