Midfacial fractures are commonly encountered in our daily clinical practice, and they cause functional problems such as malocclusion, sensory disturbance and diplopia, as well as facial deformities requiring fine esthetic outcome. So, we trauma surgeon have to diagnose and treat them precisely. In this paper, principles for utilizing several diagnostic modalities including computed tomography are clearly shown, and fundamental aspects and pitfalls in the management of various fractures (those of nasal bone, zygomatic bone, orbital floor and maxillary bone) are described in detail respectively.

Glandular odontogenic cysts (GOCs) are rare, accounting for 0.2% of all odontogenic cysts. In 1992, WHO classified a GOC as a developmental odontogenic epithelial cyst. It was classified in the same category in the WHO new classification in 2017, but its histological diagnostic criteria have changed.

　We describe two cases of GOC occurring in the mandible and compare the new standards with the old standards using the two cases we experienced.

　The new WHO classification has shown that a confident diagnosis of GOC can be made when at least 7 of 10 specific criteria are present. The condition that ‘there is no inflammatory infiltrate present within the connective tissue’ was deleted from the old classification and replaced by three new criteria. Two of the three criteria:‘intraepithelial microcysts’ and ‘multiple cystic compartments, which are sometimes present,’ focus on the assessment of early lesions. And one criterion:‘apocrine metaplasia of the luminal cells,’ is presumed to be an evaluation of differentiated cells. This has led to more accurate discrimination between GOC and other cysts and tumors, because mucous cells can be found in radicular cysts.

　Our two cases satisfy all three of the new criteria, which are expected to also be useful in clinical practice.

Recent advances in anti-retroviral therapy (ART) have led to patients with HIV infection living longer. The frequency of non-AIDS-defining malignancies (NADM), including head and neck cancer, has increased. In this study, we report our experience with the treatment of lower lip carcinoma with HIV infection. The patient was a 64-year-old-man with HIV infection. He referred to our clinic because of a lower lip tumor. We performed biopsy, and the tumor was diagnosed as squamous cell carcinoma. He received chemotherapy followed by surgical operation, tracheostomy, functional neck dissection, lower lip carcinoma resection, and reconstruction of the tongue, with no severe events. There has been no recurrence or metastasis during about 2 years.

Tumor-induced osteomalacia (TIO), also known as oncogenic hypophosphatemic osteomalacia, is caused by a tumor that secretes FGF-23, with clinical manifestations including hypophosphatemia, low serum levels of 1,25-dihydroxyvitamin D, and other symptoms of osteomalacia. Many cases of TIO are caused by phosphaturic mesenchymal tumors, but ossifying fibroma (OF) rarely been reported to cause TIO. Here we report a case of TIO caused by mandibular OF and review the literature.

　The patient was a 71-year-old man with several symptoms, muscle weakness, multiple fractures, and bone pains from the age of 43 years. He received a diagnosis of osteomalacia at 67 years of age, and was treated by phosphates and vitamin-D supplements. Because laboratory data showed high circulatory FGF-23 levels, TIO was diagnosed. Venous sampling and ⁶⁸Ga-DOTATOC PET/CT examinations demonstrated that the responsible tumor was located in the right side of the mandible. Based on the clinical diagnosis of a benign tumor of the right mandible, the lesion was surgically excised with the patient under local anesthesia, and the histopathological diagnosis was OF. After removal of the tumor, the circulatory FGF-23 level returned to the normal range, and the serum concentration of phosphate increased. The tumor has not recurred for 3 years after treatment, and patient’s activities of daily living have obviously improved.

We report a rare case of two dermoid cysts in the oral floor of an infant. A 3-year-old girl was referred to our department because of a swelling in the oral floor. Oral examination revealed a painless swelling in the oral floor. The overlying mucosa was normal, and the lesion was elastic soft on palpation. Computed tomography and magnetic resonance imaging revealed two independent cystic lesions in the oral floor. The clinical diagnosis was dermoid cyst or epidermoid cyst, and the cystic lesions were extirpated via an oral approach with the patient under general anesthesia. No adhesion to the surrounding tissues was noted.The surgical specimens were elastic soft and yellowish white. White caseous materials were contained in the cystic lesions. Microscopically, the cyst wall was lined by keratinized squamous epithelium and contained skin appendages such as hair follicles and sebaceous and sweat glands. Histopathological diagnosis of a dermoid cyst was made. No evidence of recurrence was found during 1 year 3 months of observation after surgery.