Calcium pyrophosphate dihydrate crystal deposition disease revisited

ALTHOUGH calcium pyrophosphate AL dihydrate (CPPD) crystal deposition disease is the most common crystalline arthropathy (1), the original discovery of intraarticular CPPD crystals did not occur until 1961 and 1962, when McCarty and others (2,3) identified nonurate crystals in the joint fluid of patients who had gout-like attacks of arthritis. These crystals were characterized by their weak positive birefringence at polarized light microscopy, a finding that distinguished them from the sodium mate crystals of gout. After this discovery, McCarty et al realized that radiographic characteristics of this arthropathy had been previously described by Zitnan and Sitaj (4,5), who had termed the disorder ''chondrocalcinosis polyarticularis.'' They evaluated radiographs of 27 patients with articular chondrocalcinosis, 21 of whom were members of five different Hungarian families. Since its discovery with radiography in 1958, we have learned a great deal about CPPD crystal deposition disease. and new facts about the disorder and clues to radiologic diagnosis continue to be revealed. This article will provide a review of the disease with emphasis on some of the recent findings.