Clinical evidence of the effectiveness of cochlear implantation for hearing loss with mitochondrial DNA mutation is limited. Most reports have only described short-term postoperative speech perception, which may not reflect the limitations of cochlear implantation caused by progressive retrocochlear dysfunction. The present study aimed to investigate long-term speech perception after cochlear implantation in patients with severe to profound hearing loss associated with mitochondrial DNA mutation. A retrospective chart review was performed on patients with mitochondrial DNA mutation who had undergone cochlear implantation at the Department of Otolaryngology and Head and Neck Surgery at the University of Tokyo Hospital. We extracted data on causative mutations, clinical types, clinical course, perioperative complications, and short-term and long-term postoperative speech perception. Nine patients with mitochondrial DNA mutation underwent cochlear implantation. The mean observation period was 5.5 ± 4.2 years (range, 1–13 years), and seven patients were followed for more than 3 years. Two of the seven patients who initially showed good speech perception exhibited deterioration during long-term follow-up. The absence of an acute progression of cognitive decline in patients, showing a gradual decrease in speech perception, suggests that the deterioration of speech perception was caused by progressive retrocochlear degeneration. Although most patients with mitochondrial DNA mutation maintained good speech perception for more than 3 years after cochlear implantation, retrocochlear degeneration could cause the deterioration of speech perception during long-term follow-up.

Nodular fasciitis is a benign neoplastic lesion caused by reactive proliferation of myofibroblasts, but it must be differentiated from malignant tumors. We report a case of nodular fasciitis of the buccal region in which USP6 gene rearrangement was detected for the first time in a cytological specimen. The patient was a 37-year-old woman who presented to our department for a close examination of a buccal mass that had been increasing in size for about a year. The mass was suspected to be adherent to the surrounding skin. Cytological examination revealed a spindle cell tumor (Papanicolaou Class Ⅲ) . Since the possibility of malignancy was considered, surgery was performed for a definitive diagnosis as well as treatment. The resected specimen contained an irregular-shaped mass, measuring 35×30×13mm, histopathologically composed of fascicular proliferation of spindle cells with a storiform pattern, and fluorescence in situ hybridization (FISH) analysis showed () gene rearrangement, leading to a diagnosis of nodular fasciitis. FISH analysis of the cytological specimen also showed gene rearrangement. It is worth considering FISH analysis in preoperative cytological specimens in cases where nodular fasciitis is considered.

Resection of the olfactory mucosa (OM) is sometimes unavoidable during surgery; however, it is not known whether the OM can completely recover thereafter. The aim of this study was to uncover whether the OM fully recovers after mucosal resection and describe the process of OM regeneration. 8-week-old male Sprague–Dawley rats (n = 18) were subjected to OM resection at the nasal septum; six rats were euthanized for histological examination 0, 30, and 90 days after surgery. Immunohistochemistry was performed to identify olfactory receptor neuron (ORN) lineage cells [mature and immature ORNs and ORN progenitors, and olfactory ensheathing cells (OECs)], as well as dividing and apoptotic cells. Squamous and respiratory metaplasia and inflammatory cell infiltration were also assessed. On day 30 after resection, the mucosa had regenerated, and mainly contained thin nerve bundles, basal cells, and immature ORNs, with a few mature ORNs and OECs. On day 90, the repaired nasal mucosa had degenerated into stratified squamous or ciliated pseudostratified columnar epithelia, with reducing ORNs. The lamina propria contained numerous macrophages. Partial regeneration was observed within 1 month after OM resection, whereas subsequent degeneration into squamous and respiratory epithelia occurred within 3 months. Given the poor persistence of ORNs and OECs, OM resection is likely to result in olfactory impairment. Overall, surgeons should be cautious not to injure the OM during surgery.

There are few reports in the literature of metastasis of head and neck cancer to the thyroid gland. We report a case of metastasis to the thyroid gland from supraglottic cancer. The case was an 80-year-old female, cT2N3bM0, with right cervical lymph node metastasis surrounding the carotid artery. She was treated with Pembrolizumab after radiotherapy. CT imaging after seven courses of Pembrolizumab showed an increasing low-density area in the thyroid gland. Keratinized atypical cells on cytology and histology suggested thyroid metastasis of supraglottic carcinoma. Tracheostomy was performed due to airway stenosis caused by metastatic lesions.Metastatic thyroid cancer can cause airway stenosis and bleeding as it progresses. The possibility of metastatic thyroid cancer should be considered when neoplastic lesions or thyroid function abnormalities are observed in the thyroid gland during treatment for squamous cell carcinoma of the head and neck.