Tophaceous pseudogout of the TMJ

We report a case of tophaceous pseudogout (i.e., calcium pyrophosphate dihydrate [CPPD] crystal deposition disease) in the temporomandibular joint (TMJ) that extended to the base of the skull. A 38-year-old man was referred to our hospital with mild pain in the right chin and tip of the tongue. Panoramic radiography showed a large calcified mass around the right TMJ. Computer tomography (CT) imaging revealed a large, granular, calcified mass surrounding the right condylar head and extending to the base of the skull. The mass was clinically and radiographically suspected to be a pseudogout lesion. A biopsy specimen was collected under general anesthesia to confirm the diagnosis. The mass histologically contained the deposition of numerous rod-shaped and rhomboid crystals, which suggested tophaceous pseudogout. The deposition was identified as CPPD crystal deposition, based on analysis by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). These two crystallography methods were useful in confirming the diagnosis of CPPD crystal deposition disease in the TMJ.