A Case of Diffuse Sclerosing Osteomyelitis (DSO) Initially Diagnosed as Bacterial Mandibular Osteomyelitis and Successfully Treated With Bisphosphonate Administration (Ibandronate).

Diffuse sclerosing osteomyelitis (DSO) is a non-bacterial disease of the jawbone, characterized by intermittent pain, swelling, and a mixture of osteosclerosis and osteolysis on radiographs. Its etiology remains unclear, and a standard treatment, based on clear diagnostic criteria, has not been established. We present the case of a 48-year-old male patient, who was initially diagnosed with chronic mandibular osteomyelitis due to apical periodontitis in the right lower second premolar, and underwent antimicrobial medication and surgical therapy based on computed tomography (CT), magnetic resonance imaging (MRI), and bone scintigraphy. However, the bone resorption image, with a periosteal reaction, was enlarged on CT, and the area of accumulation was also increased on bone scintigraphy. The diagnosis was switched to DSO, bisphosphonate administration (ibandronate 1 mg/month) was initiated, and the pain improved one month after administration, with the bone resorption almost disappearing after six months. The patient has been doing well for four years and four months since the initial diagnosis. This case highlights the importance of prompt diagnosis and appropriate treatment of DSO, which differs from bacterial mandibular osteomyelitis. Bisphosphonate administration is an effective treatment that contributes to the long-term course of the disease.