A case of calcium pyrophosphate dehydrate crystal deposition of the temporomandibular with synovial osteochondromatosis extending to the cranial fossa

Calcium pyrophosphate dehydrate crystal deposition (CPPD) disease is a disease in which CPPD crystals are deposited in joints.Synovial osteochondromatosis is a benign disease in which cartilage is formed in the synovial tissue, resulting in the formation of intra-articular loose bodies.We report a case of CPPD disease in the temporomandibular joint (TMJ) with synovial osteochondromatosis extending to the cranial fossa.The patient, an 80-year-old woman, presented to our department for close examination and treatment of a mass in the right TMJ.At the initial examination, a subcutaneous bone-like mass was found in the right temporalis region, and her opening disorder was observed.She had been aware of her symptoms for about 10 years.Based on clinical and imaging findings, a mass with bone resorption in the right temporomandibular head and skull base was found, and a tumor resection was performed under general anesthesia in September 2022.The bone defect in the cranial fossa was replaced using temporalis myofascial flap.The histopathological diagnosis was CPPD disease with synovial osteochondromatosis.Two years postoperatively, there was no evidence suggestive of recurrence.