Rhabdomyomatous mesenchymal hamartoma (RMH) is a rare congenital lesion frequently occurring in the skin. RMH in the oral cavity is extremely rare. We report a case of RMH on the lower surface of the tongue in a female infant with cleft palate. A 10-day-old infant was referred to our department from the department of plastic surgery in our hospital for Hotz plate treatment consultation in July 2009. In October 2010, a mass was found on the lower surface of the tongue, which could be accommodated within the same cavity. The mass measured 8 mm, had a clear border and smooth surface, and was elastic-soft. The patient’s parents refused surgery because the patient had no functional problems with eating and swallowing. The mass grew gradually, and measured about 11 × 5 mm in 2015 MRI imaging. We performed a mass excision under general anesthesia according to the patient’s instruction in December 2017. Histopathological examination showed that the mass was composed mainly of suspected tongue muscle fibers, and salivary glands were observed in its deep layer. Immunohistochemical examination showed that the muscle fibers were positive for Desmin and Myogloblin, and negative for α -SMA. Based on these examination results, the diagnosis was RMH. There was no recurrence in the 3 years 6 months after the surgical procedure.

Nivolumab, a human IgG4 PD-1 immune checkpoint inhibitor antibody, was approved in Japan for malignant melanoma in 2014, and its indications have been expanded to lung as well as head and neck cancer. However, various immune-related adverse events (irAE) have been reported, and pemphigoid was added to irAE in April 2018. To our knowledge, only four cases of oral bullous pemphigoid have been reported to date. Here, we report a case of bullous pemphigoid in a 64-year-old woman with gingival pain who was successfully treated with nivolumab for renal cancer. After the administration of nivolumab for renal carcinoma, edematous erythema and tense bullae on the palms and dorsum of the feet were observed, however biopsy revealed drug-induced lichen planus, which improved with application of topical steroids. One year after nivolumab administration, the lesions disappeared and the renal cancer treatment was completed. At three months after the end of administration of nivolumab, she experienced gingival redness, erosions, and pain; at this time she was under observation in the urology department. At five months, she was referred to our department for exacerbated gingival pain. Bullous pemphigoid was diagnosed based on a biopsy and ELISA that revealed anti-BP180 antibodies. The prognosis was good; the remission of bullous pemphigoid was obtained with prednisolone, and no recurrence of renal cancer was noted. Appropriate management of irAE during and after administration of immune checkpoint inhibitors is expected to improve the outcome of cancer treatment.

We report a case of mantle cell lymphoma (MCL) detected as a result of ill-fitting dentures. The patient was a 78-year-old male who was referred to our department due to a complaint of ill-fitting dentures. At the initial medical examination, elastic-soft masses were found on the bilateral hard palate. In the medical interview, the patient mentioned that he noticed a gradual enlargement without pain or discomfort. Detailed examination by computed tomography and magnetic resonance imaging revealed multiple tumor lesions in the right oropharynx and hard palate, as well as perineural invasion; thus, lymphoma was suspected. A biopsy of the mass on the hard palate was performed, and immunohistochemical staining led to a definitive diagnosis of MCL. Chemotherapy was administered in the department of hematology and oncology at our hospital, and the mass on the hard palate completely disappeared. MCL, a rare type of lymphoma, arose at an atypical site in this patient, making diagnosis difficult. MCL has been reported to have a high recurrence rate, therefore requiring regular and continuous follow-up.

The incidence of supernumerary teeth appearing in the third molar tooth regions is reported to be 0.02～2.2%, and while most of which are found in the unilateral maxilla, they rarely occur in the mandible, and bilateral mandible occurrence is extremely rare. Here we report a case with the supernumerary teeth distal to the third molar teeth in the bilateral mandible. The patient was a 27-year-old man who was found to have maxillomandibular third molar teeth and supernumerary teeth in the bilateral mandible, and visited our department for teeth extraction. Panorama radiograph and CT images showed that the patient had an impacted supernumerary tooth above a horizontally impacted wisdom tooth in his right mandible. He also had an impacted wisdom tooth and a buccolingual impacted supernumerary tooth in the left mandible. We removed the bilateral maxillomandibular third molar teeth and the bilateral mandibular supernumerary teeth under general anesthesia management to prevent infection. About five months have passed since the operation, and no infection or incomplete healing of the extraction sockets has been observed, and the course is good.

We report a case of botryoid odontogenic cyst of the anterior maxilla. A 49-year-old woman with localized swelling in the anterior maxillary gingiva was referred to our department for consultation. Orthopantomography and CT revealed a well-demarcated intraosseous unilocular cystic lesion in the right anterior maxilla, separated from the central embedded supernumerary tooth. A cystectomy was performed according to the clinical diagnosis of bone cyst of the upper jaw. Histopathologically, the lesion was diagnosed as a botryoid odontogenic cyst. The postoperative course was uneventful, with no signs of recurrence four years after the surgery.