Contemporary issues relating to calcium pyrophosphate deposition disease.

Calcium pyrophosphate deposition (CPPD) disease is a common crystalline arthritis that has historically been under-studied compared to other rheumatic diseases including gout. For decades, the presence of CPPD in joints has been consider of uncertain clinical importance, with conflicting reports on whether CPPD leads to osteoarthritis progression or other adverse outcomes. A growing body of literature in the past five years has challenged the prevailing view of CPPD disease as "just chondrocalcinosis." These findings have arrived together with recent developments in classifying CPPD disease for research studies, advances in quantification of CPPD on imaging studies, consensus on outcomes to be measured in CPPD disease clinical trials, newly-identified genetic associations, and updates in the nomenclature for this crystalline arthritis. This review summarizes key updates in each of these realms.