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Bone metabolism is strictly regulated, and impaired regulation caused by hormonal imbalances induces systemic bone loss. Local bone loss caused by tumor invasion into bone is suggested to be induced by the generation of cytokines, which affect bone metabolism, by tumor cells. The major cause of systemic and local bone losses is excess bone resorption by osteoclasts, which differentiate from macrophages by receptor activator of nuclear factor kappa-B ligand (RANKL) or tumor necrosis factor-alpha (TNF-α). We previously found a novel pathway for tumor-induced osteoclastogenesis targeting osteoclast precursor cells (OPCs). Tumor-induced osteoclastogenesis was resistant to RANKL and TNF-α inhibitors. In the present study, we confirmed that exosomes derived from oral squamous cell carcinoma (OSCC) cells induced osteoclasts from OPCs. We also showed that the depletion of exosomes from culture supernatants of OSCC cells partially interfered with osteoclastogenesis, and cannabidiol, an innoxious cannabinoid without psychotropic effects, almost completely suppressed tumor-induced osteoclastogenesis. Osteoclastogenesis and its interference by cannabidiol were independent of the expression of nuclear factor of T cell c1 (NFATc1). These results show that osteoclastogenesis induced by OSCC cells targeting OPCs is a novel osteoclastogenic pathway independent of NFATc1 expression that is partially caused by tumor-derived exosomes and suppressed by cannabidiol.

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Background: Primary intraosseous carcinoma (PIOC), NOS is an odontogenic carcinoma with unknown etiology. Its diagnosis may be used when central jaw carcinoma cannot be categorized as any other type of carcinoma. Further information on this extremely rare tumor is needed to improve our understanding and evaluate the classification of odontogenic carcinomas. Case presentation: We herein presented two patients with PIOC, NOS with different clinical and histopathological features and analyzed gene mutations in these patients using next-generation sequencing (NGS). The typical PIOC, NOS case had many histopathological similarities to oral squamous cell carcinoma (OSCC), including the missense point mutations of TP53 Glu285Val, KDR Gln472His, and APC Pro1433Leu, which are similar to those in other cancers; however, no mutations were detected in the other patient with an atypical presentation of PIOC, NOS, which was derived from a precursor cystic lesion with similarities to both ameloblastic carcinoma and OSCC. Conclusions: Genetic analysis suggested that these two PIOC, NOS cases have different features and can be subcategorized.

Background Intravesical administration of Bacillus Calmette–Guérin (BCG) has proven useful for treatment and prevention of recurrence of superficial bladder cancer and in situ carcinoma. However, fatal side effects such as disseminated infections may occur. Early diagnosis and accurate therapy for interstitial pneumonitis (IP) are important because exacerbation of IP triggered by infections is the major cause of death. Although some fatality reports have suggested newly appeared IP after intravesical BCG treatment, to our knowledge, there are no reports which have demonstrated acute exacerbation of existing IP. Moreover, autopsy is lacking in previous reports. We report the case of a patient with fatal IP exacerbation after BCG instillation and the pathological findings of the autopsy. Case presentation A 77-year-old man with a medical history of IP was referred to our hospital because of fever and malaise. He had received an intravesical injection of BCG 1 day before the admission. His fever reduced after the use of antituberculosis drugs, so he was discharged home. He was referred to our hospital again because of a high fever 7 days after discharge. On hospitalisation, he showed high fever and systemic exanthema. Hepatosplenomegaly and myelosuppression were also observed. Biopsies revealed multiple epithelioid cell granulomas with Langhans giant cells of the liver and bone marrow. Biopsy DNA analyses of Mycobacterium bovis in the bone marrow, sputum, and blood were negative. His oxygen demand worsened drastically, and the ground-glass shadow expanded on the computed tomography scan. He was diagnosed with acute exacerbation of existing IP. We recommenced the antituberculosis drugs with steroid pulse therapy, but he died on day 35 because of respiratory failure. The autopsy revealed a diffuse appearance of multiple epithelioid cell granulomas with Langhans giant cells in multiple organs, although BCG was not evident. Conclusions We report the first case of acute exacerbation of chronic IP by BCG infection. This is also the first case of autopsy of a patient with acute exacerbation of existing IP induced by intravesical BCG treatment. Whether the trigger of acute IP exacerbation is infection or hypersensitivity to BCG is still controversial, because pathological evidence confirming BCG infection is lacking. Physicians who administer BCG against bladder cancer should be vigilant for acute exacerbation of IP.