Diagnosis: Tophaceous pseudogout (calcium pyrophosphate deposition disease [CPDD]) of the TMJ
Tophaceous pseudogout, which is composed of calcium pyrophosphate dihydrate crystals, is also termed chondrocalcinosis. It affects synovial joints that are defined by the presence of a joint capsule surrounding the articulating surface and lubricating synovial fluid. These features are not present in cartilaginous joints (symphyses) or fibrous joints (sutures). There are 7 types of synovial joints, and the TMJ is categorized as a condyloid-type synovial joint. Calcium pyrophosphate deposition disease was first described in synovial joints in 1962 by Kohn et al1 in a patient with goutlike symptoms without sodium urate crystals. Pseudogout of the head and neck region is rare, and involvement of the TMJ was first described by Pritzker et al2 in 1976. The risk of CPDD increases with age, with most cases occurring after the age of 76 years. The pathogenesis is not completely understood, but chondrocytes are thought to produce inorganic pyrophosphate.3
Pathology Quiz Case 2: Diagnosis. Arch Otolaryngol Head Neck Surg. 2012;138(9):874–875. doi:10.1001/archotol.138.9.874
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