EDITORIALS Calcium Pyrophosphate Dihydrate Crystal Deposition Disease: Nomenclature and Diagnostic Criteria

Browning T H E VARIETY OF NAMES suggested for the condition associated with deposits of calcium pyrophosphate dihydrate crystals is exceeded only by the variations of its clinical presentation. "Articular chondrocalcinosis" was used by Zitrian and Sitaj to designate the highly characteristic articular radiodensities used by them as the definitive diagnostic feature (1). "Pseudogout " was first used by me in these pages 15 years ago because we had discovered microcrystals of calcium pyrophosphate dihydrate in the leukocytes of fluid from inflamed joints (2). These seemed analogous to the sodium urate crystals associated with true gout that we had described previously. Both the diagnosis of "gout " and "pseudogout " therefore depended on precise identification of crystals. The radiologic finding of typical punctate and linear radiodense deposits in hyaline or fibrous cartilage, while suggestive of the kind of crystal, could never be as specific diagnostically a