The author analyzed the outcome in 91 patients undertaken with surgical treatment and proposed the concept and strategy for temporomandibular joint (TMJ) dislocation in especially elderly subjects. The patients composed of 20 long-standing and 80 recurrent TMJ dislocation, in which the majority were medically compromised characteristics and dementia. Applied procedures were as follows; arthroscopic eminoplasty (AE), open arthrotomy with eminectomy (E), eminectomy with additional procedures (E+α), tethering procedure employing screws and wire, and zygomatic arch down fracture procedure.

　The overall outcome revealed 82% of success rate and the results indicated that, 1. Eminectomy and zygomatic down-fracture operation were both excellent procedures, 2. Elderly patients have trend to associate dyskinesia which may contribute lower surgical outcomes, 3. Documented complication with facial nerve paresis would be slight degree, 4. Different approach should be considered in different types with recurrent and long-standing styles, 5. The modified approach under local anesthesia needs to be performed with a high care managements.

This article describes two different surgical procedures for recurrent temporomandibular joint dislocation: eminectomy preserving the posterior slope of the eminence and augmentation eminoplasty with a newly designed titanium plate and artificial bone complex. After non-surgical attempts at prevention of dislocation failed, surgical intervention was considered. Both procedures were performed under general anesthesia with nasotracheal intubation.

　Eminectomy preserving the posterior articular slope: Surgical resection of the anterior articular slope required precise cuts with piezoelectric surgery. The slope was removed with an angled-up cutting surface from the inferior border of the zygomatic arch to the lower end of the eminence. The advantages of this surgical procedure were its relative simplicity and maintenance of the posterior functional surface.

　Augmentation eminoplasty: The newly designed titanium plate has high mechanical strength. However, plate augmentation alone without artificial bone coverage caused anterior condylar bone resorption. The plate covered with the artificial calcium phosphate bone was used to avoid condylar resorption. The artificial bone has high compressive strength. The complex fixed with the zygomatic arch prevented dislocation without any plate fracture or artificial bone breakage.

　There were no major disadvantages of these procedures. The postoperative course was uneventful, with a stable joint state.

　Both procedures are reliable for the management of recurrent temporomandibular joint dislocation.

Recently, the number of patients of habitual dislocation of the temporomandibular joint is increasing, along with an increasing number of elderly people with systemic diseases such as cerebral infarction and dementia. Although invasive treatment is often performed when noninvasive treatment is ineffective for habitual dislocation of the temporomandibular joint, the criteria on which surgical methods should be chosen is not clear. In addition, since the patient’s general condition is often poor, minimally invasive surgery that can be performed with local anesthesia is desirable.

　We investigated treatment methods for habitual dislocation of the temporomandibular joint in our department and their problems. Forty-two patients were enrolled in this study. Their mean age was 79 ± 14 years, with a range of 36 − 95 years. All patients had an underlying disease such as cerebral infarction, dementia, and Parkinson’s disease. The Buckley-Terry method or eminectomy were performed under local anesthesia in 26 joints of 16 patients and 44 joints of 26 patients, respectively. Recurrence occurred in 5 of 16 patients (6/26 joints; 23.1%) after the Buckley-Terry method, and 2 of 26 patients (2/44 joints; 4.5%) after eminectomy (p = 0.045). The causes of recurrence after the Buckley-Terry method was the deformation of titanium plates. Temporarily peripheral facial nerve palsy developed in 3 of 16 patients (3/26 joints; 11.5%) treated by the Buckley-Terry method, but not in any patient treated by eminectomy (p = 0.048).

　Our results suggested that eminectomy is a more useful treatment than the Buckley-Terry method for habitual dislocation of the temporomandibular joint, especially in elderly patients with underlying diseases. However, since we found a few recurrent cases after eminectomy, there are still many problems to be considered, such as the criteria for adaptation and the approach to these cases.

Odontogenic myxoma is a rare, benign and locally aggressive tumor of the jaw. The classification of odontogenic tumors by the World Health Organization (2017) uses the terms “odontogenic myxoma” and “odontogenic fibromyxoma” interchangeably, and states that fibromyxomas tend to have more amounts of collagen fibers than myxomas. They usually occur in the third decade of life and females have higher predilection than males. The incidence among children is lower.

　We report a case of a 3-year-old girl with the diagnosis of odontogenic fibromyxoma of the right inferior border of the mandible. The girl attended our clinic because her mother noticed swelling of her jaw when she was brushing the girl’s teeth. Computed tomography revealed a 16×11 ×13 mm unilocular radiolucent lesion involving the right inferior border of the mandible. The lesion presented lower than the inferior alveolar canal. The treatment consisted of tumor enucleation followed by curettage of the cavity under general anesthesia. The histopathological diagnosis was odontogenic fibromyxoma.

　Seven years after surgery, the girl is asymptomatic and there is no absence of permanent teeth on her mandible.

Malignant peripheral nerve sheath tumors (MPNSTs) are very rare malignant neoplasia that arise from the peripheral nervous system and show nerve sheath differentiation. We report a case of primary malignant peripheral nerve sheath tumor of the mandibular gingiva.

　A 53-year-old male was referred to our hospital presenting with a mass and pain in the mandibular gingiva. He had no appreciable disease and paralysis of the lower lip.

　Computed tomography showed resorption of the mandible but no obvious lymph node metastasis.

　Biopsy revealed a possible invasive unusual neuroectodermal tumor. Surgical resection was performed and the frozen section showed negative margins.

　Histology revealed atypical spindle cells with clear chromatin and clear nucleolus which had proliferated and loosely infiltrated, but the cell boundaries were unclear. Immunohistochemical staining showed positive results for S-100 protein, p53, and vimentin, but negative results for pan-cytokeratin (AE1 / AE3), Melan A, and desmin. The Ki-67 labeling index was 10%. Accordingly, we diagnosed a low-grade peripheral nerve sheath tumor of the mandibular gingiva.

　There were no signs of recurrence or metastasis at two years postoperatively. MPNSTs have poor prognoses and require careful follow-up.

Cystadenocarcinoma (adenocarcinoma NOS) is a rare disease among salivary tumors. We report a case of cystadenocarcinoma originating from the palatine gland, with references. A 69-year-old man with an increasing tumor in the right palate was referred to our department. The patient had a 35 × 20 × 5 mm dome-like mass on the right hard palate, with a smooth and partially blue-violet surface. Contrast-enhanced CT imaging showed a mass lesion with a well-defined boundary and bony resorption beneath the right hard palatine mucosa. Contrast-enhanced MRI imaging showed a mass lesion with a high signal on T2W1 and high ADC value, which had a marginal capsule and an internal septum structure. Biopsy indicated a low-grade salivary gland tumor including a mucoepidermoid carcinoma. The tumor was resected under general anesthesia with the diagnosis of a malignant salivary tumor on the right palate. The histopathological diagnosis was cystadenocarcinoma. At twenty-five months after surgery, no recurrence or metastasis has been observed.

The first case of secretary carcinoma was reported by Skálová et al. in 2010, which was reported as mammary analogue secretory carcinoma (MASC) due to being similar to mammary secretory carcinoma. Secretory carcinoma was newly classified as salivary gland tumor in the WHO classification (4th edition). We report a case of secretary carcinoma arising in the labial gland. A 56-year-old woman visited our hospital with the complaint of an upper labial mass, first noticed in 2017. She had already undergone biopsy in another hospital and was diagnosed with adenocarcinoma NOS histopathologically. She was referred to our department in April 2018. Tumor resection and reconstructive surgery were carried out under general anesthesia and the histopathological diagnosis was secretary carcinoma. After one year and 11 months there has been no recurrence or metastases. The strongest identifying feature of secretory carcinoma is the ETV6-NTRK3 fusion gene, and diagnosis can be confirmed by performing genetic testing, but it is difficult to perform in all cases. The S-100 protein, vimentin, etc. are said to assist diagnosis, and it is thought that further cases should be examined in the future.

This report describes a case of intravascular papillary endothelial hyperplasia (IPEH) arising in the upper lip.

　A 7-year-old girl was referred to our department because of painless swelling of the upper lip in October 2015. She had suffered a bruise on her upper lip 4 months before consultation. Physical examination revealed an elastic hard submucosal mass, measuring 20 × 10 mm, on the left side of the upper lip. Magnetic resonance imaging (MRI) indicated a well-defined neoplastic lesion. The lesion was clinically diagnosed as a benign tumor and was surgically removed under general anesthesia. The histopathological diagnosis of the excised specimen was IPEH (pure form).

　IPEH is very difficult to clinically diagnose, since it shows various clinical findings. In previous reports, there are some cases in which IPEH was confirmed by surgical resection with a clinical diagnosis of hemangioma. It has been pointed out that its occurrence mechanism is related to a history of trauma, and it was the same in our case.

　IPEH (pure form) rarely recurs after complete resection. In our case, four years have passed since the operation and there is no sign of recurrence.