Primordial odontogenic tumor (POT) is a benign mixed epithelial and mesenchymal odontogenic tumor included into the current World Health Organization (WHO) classification of Head and Neck tumours in 2017. As far as the authors have confirmed, only eight cases of this tumor have been reported so far. This paper reports a case of POT that occurred in the right mandible of a 5-year-old patient. Panoramic radiograph showed a well-defined homogeneous radiolucency displacing the unerupted second deciduous molar to the deep part of the mandible. Histopathologically, the tumor was composed of cell-rich mesenchymal tissue with myxoid areas, surrounded by columnar epithelium and non-keratinized cuboidal epithelium in the outer layers. The histopathological diagnosis was POT. The expression patterns of cytokeratins (CK) 14, 18, 19, vimentin and CD34 suggested that the grade of differentiation of the POT was approximately equivalent to that of normal primary tooth germ tissues in cap stage to late bell stage.

a b s t r a c tWe encountered a patient with a huge osteoma extending over half of the mandible, which was incidentally discovered on a head-and-neck computed tomography (CT) by an otolaryngological examination for vertigo.A tumorous lesion of the right mandible was noted, and the patient was referred to our department. The tumor extended from the median mandible over the right anterior margin of the ramus of the mandible.To improve the abnormal intraoral morphology, tumor resection and orthopedic surgery were performed. The histopathological diagnosis was a cancellous osteoma.Dentures were attached after surgery, and the postoperative course has been favorable with no tumor re-enlargement.

Radiation therapy (RT) plays a significant role in the management of head and neck malignancies. This study aimed to review the clinical symptoms and various imaging findings of osteoradionecrosis (ORN) and provide a clinical perspective on the development of ORN. The retrospective cohort was composed of 57 sites in 54 patients who had a history of RT and suspected ORN and 48 sites in 45 patients who were confirmed to have ORN. Image analyses included computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET)/CT, bone scintigraphy, and single-photon emission CT (SPECT). The irradiated tissue was damaged by RT, and the extent of damage was correlated with clinical symptoms. The bone marrow showed sclerotic changes and the devitalized bone showed bone resorption after invasive stimulation. Chronic trismus and pathological fracture are considered severe conditions, typically occurring in the last stage of ORN. Furthermore, neurological symptoms were an important sign of tumor recurrence, since diagnostic imaging was difficult. The possible treatment options vary depending on the stage of ORN. We speculate that bone sclerosis reactions and bone resorption are sequential reactions that seem to be protective measures of the bone to radiation injury.

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Oral diverticulum is rarely encountered, and the histopathological findings are unclear. We herein report a case of an oral diverticulum and describe its histopathological findings. A buccal mucosal outpouching was observed in a 66-year-old man. Food debris was seen within the outpouching. Under the clinical diagnosis of a diverticulum-like lesion, excision of the outpouching was performed through an intraoral incision to stop food impaction. Histopathological examination revealed that the excised lesion was a true diverticular structure composed of a keratinising, squamous epithelial lining with a surrounding fibrous connective tissue wall, with inflammatory cell infiltration and haemorrhage. The histopathological diagnosis was a diverticular pouch of the buccal region. Clinicians should be aware of this lesion to ensure correct diagnosis and treatment.