Complex odontoma is classified as odontogenic epithelium with odontogenic ectomesenchyme with or without hard tissue formation according to the WHO histological classification of odontogenic tumors (2005). It rarely occurs in the maxillary sinus.

　We describe an extremely rare huge complex odontoma extending to the right maxillary sinus of a child.

　A 12-year-old girl was referred to our department for further evaluation of the right maxillary sinus. Panoramic radiography revealed a radiopaque mass in the right maxillary sinus. A computed tomographic scan showed a high density mass in the maxillary sinus. The lesion was enucleated with the patient under general anesthesia. The lesion resected from the maxillary sinus measured 50 × 35 × 30 mm and was light gray and bony hard. The definitive histopathological diagnosis was a complex odontoma.

　As of 4 years and 3 months after the operation, the patient showed no signs of recurrence.

Castleman's disease (CD) usually occurs in the mediastinum and the hilar region and relatively rarely occurs in the head and neck region. We report a case of CD arising in the right submandibular region in a 26-year-old woman. The patient had symptoms of swelling in the right submandibular region that had been present for half a year. On examination, a nontender movable mass of 25 × 20 mm was palpated in the right submandibular region. Computed tomography revealed a well-demarcated mass measuring 30 × 20 mm in the right submandibular region, and all laboratory data were within normal range. The mass was removed with the patient under general anesthesia. Histopathologically, the mass was diagnosed as a hyaline-vascular type of CD. There was no recurrence at follow-up 7 years after surgery.

Essential thrombocythemia (ET) is a rare chronic myeloproliferative neoplasm that shows thrombosis and bleeding symptoms with an increase in the platelet count. JAK2 mutation is suggested to be involved in its pathogenesis. We report a case of ET with the JAK2 gene mutation that presented with postextraction bleeding. The patient was a 68-year-old man who was referred to our hospital 3 days after tooth extraction because of continuous postextraction bleeding, facial swelling, and trismus. Laboratory findings showed thrombocytosis; the platelet count was 103 × 10⁴/μL. A review of the patient's history revealed that a bone marrow biopsy and genetic tests had been performed at the Department of Hematology before tooth extraction because of a hematological disorder. We diagnosed ET with JAK2 gene mutation on the second day after admission. Because it was difficult to stop the hemorrhage, a total of 60 units of platelets were transfused, and the excessive hemorrhage stopped 10 days after the extraction. This approach thus appears to be effective for patients with ET who have bleeding. Hydroxyurea was administered as ET therapy 1 month later, and the platelet count decreased.

We describe a large dentigerous cyst arising from an inverted and impacted maxillary central supernumerary tooth in an adult patient. The patient was a 60-year-old man who consulted our department for the detailed examination of a large radiolucent region in the maxilla. This finding had been observed on a panoramic radiograph recorded during a visit to his local dental clinic. Computed tomography revealed an inverted and impacted maxillary central supernumerary tooth and a unilocular radiolucent region measuring approximately 50 × 34 × 36 mm, which encompassed the tooth crown within the lumen. After a biopsy and the diagnosis of a dentigerous cyst, the patient underwent cystectomy and extraction of the supernumerary tooth under general anesthesia. The histopathological diagnosis was a dentigerous cyst. As of 2 years 6 months after surgery, the patient has been progressing well, with no signs of recurrence.

We report a case of recurrent acute hemorrhagic rectal ulcer (AHRU) associated with prolonged bedridden condition due to worsening osteoradionecrosis of the jaw (ORNJ). An 83-year-old woman who had previously received chemoradiotherapy for oropharyngeal cancer was referred to our hospital to treat a perimandibular abscess due to ORNJ. The patient also had a medical history of brain infarction and bilateral femoral fractures.

　The abscess was controlled by pus drainage, debridement, and administration of antibiotics. On the 3^rd hospital day, hematochezia abruptly occurred, colonoscopy revealed AHRU, and endoscopic hemostasis was performed. Then, rebleeding developed because of bedridden condition and worsening nutritional disorder. Nutritional support was continuously provided by a combination of intravenous and enteral nutrition, leading to improvement of undernutrition. The patient eventually underwent hemimandibulectomy without reconstruction.

　Elderly patients with atherosclerosis-related comorbidities are at risk for AHRU when bedridden because of their vulnerability to rectal ischemia. Bedridden patients with severe oral diseases such as progressive oral cancer and ORNJ also have a potential risk of AHRU.

Mixed connective tissue disease (MCTD) was originally defined in 1972 by Sharp et al. as a connective tissue disorder characterized by the presence of high titers of anti-U1-ribonucleoprotein (U1-RNP) antibody in combination with clinical features seen in systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and polymyositis (PM). We report a case of MCTD diagnosed after hemorrhage from a tooth extraction wound. A 74-year-old man with bleeding from the cavity remaining after extraction of the right lower lateral incisor was referred to our department. Although there was no history of hemorrhagic disorders, initial laboratory data showed a platelet count of 0.3 × 10⁴/μL. He was hospitalized immediately and given concentrated platelet preparations. Bone marrow aspiration showed no abnormality. Thereafter, Raynaud's symptom, localized sclerema of the finger, and high titers of anti U1-RNP antibody were observed in the patient. He was consequently was given a diagnosis of hemorrhage from a tooth extraction wound caused by immune thrombocytopenia (ITP) associated with MCTD. He received prednisolone and Helicobacter pylori eradication therapy. The platelet count gradually increased, and postoperative bleeding was controlled by local hemostatic measures using a gingival pack.

Odontogenic myxofibroma occurs relatively infrequently in children, but its recurrence rate is relatively high. It is therefore difficult to determine the treatment policy in an appreciable number of cases. We describe an 8-year-old boy with odontogenic myxofibroma of the right side of the mandible. The patient was referred to our hospital because of a right mandibular radiolucent lesion. On examination, there was gingival swelling extending from the lower right first molar to the anterior margin of the ramus, but no obvious extraoral abnormality. Histopathological examination of a biopsy specimen resulted in the diagnosis of odontogenic myxofibroma. In November 2013, the lesion was removed with the patient under general anesthesia by conservative surgical treatment with enucleation and curettage of the bone around the lesion. The postoperative course was uneventful, and there was no evidence of recurrence of the lesion 3 years 6 months after the operation.