Sudden sensorineural hearing loss (SSNHL) is routinely encountered and is one of the most common emergent diseases in otolaryngology clinics. However, the etiology of SSNHL remains unclear. Due to the inaccessibility of the living human inner ear for biopsy, studies investigating the etiology of SSNHL have been performed by analyzing data obtained from examinations using peripheral blood or imaging. We updated the findings obtained from serological, magnetic resonance imaging, genetic, and viral examinations to reveal the etiology of SSNHL. Regarding viral examination, we focused on sensorineural hearing loss associated with coronavirus disease (COVID-19) because the number of correlated reports has been increasing after the outbreak. The updated findings revealed the following three possible mechanisms underlying the development of SSNHL: thrombosis and resulting vascular obstruction in the cochlea, asymptomatic viral infection and resulting damage to the cochlea, and cochlear inflammation and resulting damage to the cochlea. Thrombosis and viral infection are predominant, and cochlear inflammation can be secondarily induced through viral infection or even thrombosis. The findings about sensorineural hearing loss associated with COVID-19 supported the possibility that asymptomatic viral infection is one of the etiologies of SSNHL, and the virus can infect inner ear tissues and directly damage them.

Background: We have recently developed the correlative light and electron microscopy of hematoxylin and eosin (H&E)-stained glass slides using the ‘NanoSuit’ method. The aim of this study is to explore the utility of the new NanoSuit-correlative light and electron microscopy method combined with scanning electron microscopy-energy dispersive X-ray spectroscopy elemental analysis for the diagnosis of lanthanum phosphate deposition in the H&E-stained glass slides. Methods: Nine H&E-stained glass slides of the upper gastrointestinal tract mucosa containing the brown pigmented areas by light microscopic observation, which were suspected as lanthanum phosphate deposition, were observed and analyzed by scanning electron microscopy-energy dispersive X-ray spectroscopy using the NanoSuit-correlative light and electron microscopy method. Results: In all nine slides, the new NanoSuit-correlative light and electron microscopy method combined with scanning electron microscopy-energy dispersive X-ray spectroscopy revealed the accumulation of both lanthanum and phosphorus in the tissue area corresponding to the brown pigment deposition. In addition to the existence of lanthanum phosphate in the stomach and duodenum, known target organs, we observed deposition in the esophagus for the first time. Furthermore, we observed lanthanum phosphate deposition in the background mucosa of stomach containing primary adenocarcinoma. Conclusions: Scanning electron microscopy-energy dispersive X-ray spectroscopy analysis using the NanoSuit-correlative light and electron microscopy method is useful for the diagnosis of lanthanum phosphate deposition in the H&E-stained glass slides. Lanthanum phosphate deposition occurs not only in the stomach and duodenum but also in the esophagus.

Ion-exchange resins are commonly used to treat complications such as hyperkalemia, hyperphosphatemia, and hypercholesterolemia. Gastrointestinal complications may occur as side effects of such treatments. Sodium and calcium polystyrene sulfonate (PS-Ca) are cation-exchange resins comprising an insoluble structure that binds to potassium ions in the digestive tract and exchanges them with sodium and calcium ions, respectively, to promote their elimination. PS crystals are rhomboid, refractive, and basophilic in hematoxylin and eosin staining. To differentiate PS crystals from other ion-exchange resin crystals such as sevelamer and cholestyramine, periodic acid–Schiff, Ziehl–Neelsen, and Congo red staining are usually performed. Here, correlative light and electron microscopy (CLEM)-energy-dispersive X-ray spectroscopy and the NanoSuit method (CENM) was applied to perform a definitive identification of ion-exchange resins. CENM could detect sulfur in PS crystals without destroying the glass slides. Notably, PS retained its ion-exchange ability to bind potassium in paraffin sections. Differential diagnosis of anion-exchange resins, such as sevelamer and cholestyramine, was possible using these characteristics. The phosphorus:carbon ratio was higher in sevelamer than in cholestyramine after soaking paraffin sections in a phosphate solution. Therefore, CENM may be used for the differential pathological diagnosis of ion-exchange resins in paraffin sections.

Oral allergy syndrome (OAS) is characterized by an immediate allergic reaction that mainly or partially affects the oral mucosa, pharynx, or lips, and it is usually caused by ingesting fresh fruits or vegetables. Most patients with OAS also have allergic rhinitis due to pollen. As allergic rhinitis is increasingly prevalent in the Japanese population and the age at disease development is decreasing, morbidity associated with OAS among the younger population is likely to increase. However, there is little information about the prevalence of this disease among Japanese children, specifically the influences of residency in regions with different environments. To investigate the prevalence of OAS and seasonal allergic rhinitis (SAR) among Japanese children and evaluate the relationship between OAS and SAR. We administered a questionnaire-based survey among children aged 7-15 years, living in 4 cities in central Japan. The questionnaires were administered to 4103 children and completed by 3365 (82.0%). Overall, 524 children (15.6%) reported OAS-like symptoms after ingesting fruits or vegetables. The prevalence of seasonal SAR and oral symptoms significantly differed among the 4 cities. The total prevalence of oral symptoms co-occurring with SAR was 24.4%, which was significantly higher than the prevalence of symptoms occurring without SAR (10.2%, p < 0.001). Herein, oral symptoms were more likely to occur in patients with SAR than in those without SAR. The prevalence of SAR and food-induced oral symptoms significantly differed among the regions, suggesting they might be affected by regional differences in lifestyles and flora.

Laryngeal papillomatosis is caused by infection with human papillomavirus (HPV) type 6 and/or 11. Laryngeal papillomatosis recurs frequently, and malignant transformation occurs in 1.6%-4% of the cases. Surgery is the treatment of first choice. While adjuvant therapies such as interferon, Chinese medicines, proton pump inhibitors, indole 3 carbinol, cidofovir and vaccines have been tried, none has come to be positioned as the standard of care. We report seven patients with laryngeal papillomatosis who underwent multiple surgeries. All were men. The surgery was performed in combination with two or three of the following: use of an electric scalpel, CO₂ laser, YAG laser, sharp resection, and intralesional injection of cidofovir. Intralesional injection of cidofovir after resection was performed in four cases, and remission was achieved in three of these cases. Cidofovir is an unapproved drug in Japan and is not yet approved for use in cases of laryngeal papillomatosis in other countries. However, the outcomes in our cases and other reports suggest that intralesional injection of cidofovir is effective. HPV6 (n=5), HPV11 (n=1) and HPV negative (n=1) detected respectively. Malignant transformation occurred in one case and HPV negative. Moreover, p16 immunohistochemistry was performed in all cases. However, no relation with number of operations and HPV status was found. The life cycle of HPV in laryngeal papillomatosis is largely unknown, and there is no consensus on methods of treatment other than surgery. More research is needed to elucidate the life cycle of HPV and the pathophysiology of laryngeal papillomatosis.

Key Clinical Message: A 35‐year‐old male presented with recurrent respiratory papillomatosis. Human papillomavirus type 11 was detected from all sites of tumor tissue DNA by PCR. The pre‐surgery cell‐free DNA (cfDNA) viral load (3.33 × 10³ copies/ng DNA) fell below the post‐surgical detection limits on achieving remission, suggesting cfDNA's potential as a biomarker.