Calcium Pyrophosphate Deposition Disease of the Temporomandibular Joint Extending into the External Auditory Canal and the Middle Ear, Coexisting with Otosclerosis: A Case Report.

Calcium pyrophosphate deposition disease (CPPD) is caused by CPP crystals and rarely forms tumors in joints. The authors describe a case of tumoral CPPD in the temporomandibular joint (TMJ), extending into the external auditory canal (EAC) and the middle ear. A 71-year-old man was referred to the department with a tentative diagnosis of CPPD in the right TMJ. Computed tomography showed the mass extending into the EAC, tympanic cavity, and bony Eustachian tube, with opacification of the mastoid cells. The audiogram revealed bilateral mixed hearing loss, suggesting the coexistence of bilateral otosclerosis. Partial resection of the mass and simultaneous implantation of a Baha® on the same side were performed. Histopathological findings revealed indistinct crystals in the surgical specimens. Calcium pyrophosphate crystals were identified using thin-film X-ray diffraction (XRD) analysis. The comorbidity of CPPD and otosclerosis in the same ear is a rare condition. Considering the unpredictable nature of CPPD, the authors opted for partial resection of the lesion involving the EAC and the middle ear to avoid any complications. Due to coexisting otosclerosis, Baha® played an important role in the auditory management of bilateral mixed hearing loss in this patient.