Otologic and temporal bone surgery requires a good understanding of the complex surgical anatomy of the temporal bone. Even with sufficient preoperative imaging and surgical anatomy training, the orientation of the anatomy is frequently lost during the surgery in cases with severe anomalies and surgery at unfamiliar surgical sites. Moreover, in recent years, otologic and temporal bone surgery has begun to deal with various auditory implants, which require precise positioning to obtain better outcomes. Therefore, it is essential to evaluate the surgical field closely intra-operatively. For this purpose, computed tomography (CT) is appropriate because most otologic and temporal bone surgical areas contain much bone. Recently, the improvement of a flat panel to detect radiation signals has enabled the development of a small CT scanner for so-called cone-beam CT (CBCT). Its scan head rotates around the head of the patient sitting on a chair and obtains images. To use a CBCT scanner for patients lying on the operating table, a mobile CBCT (mCBCT) scanner with a light but firm scan head, with its rotating axis parallel to the ground, has been developed. It can be used in any operating room and at any time during surgery. Moreover, its low contrast resolution contributes to low metal artifacts in the images. We use mCBCT in various situations in otologic and temporal bone surgery. For example, we evaluate the positions of cochlear implant electrodes, especially in cases with cochlear anomalies, and assess the existence of tip fold-over during surgery. We also use it to confirm the position of the endolymphatic sac during endolymphatic sac surgery for Meniere’s syndrome. mCBCT is also used to quickly and precisely register image-guided surgery systems during surgery in cases with severe anomalies and for operations involving unfamiliar sites. In addition to these examples, different applications of mCBCT are expected to be developed in the future for safer and more effective outcomes of otologic and temporal bone surgery.

A 34-year-old woman presented with a history of dizziness, jerking of the eyes, and gait disturbance upon waking up. Two days later, she visited an otolaryngology doctor in her neighborhood, and on the same day she was referred to the otolaryngology department of Toyama Red Cross Hospital. She had had a headache and fever of 38 degrees a week prior to the onset of symptoms, which had soon resolved. Gaze nystagmus examination revealed a high frequency of pendular abnormal eye movements in the left-right direction. She showed bursts of horizontal saccadic oscillations with an amplitude of 7°–14°. A single burst of oscillations lasted up to 6 seconds. Caloric test showed loss of visual suppression in both ears. MRI revealed no significant abnormalities. She was able to walk on her own.

For the purpose of excluding central dizziness, she was referred to the Department of Otorhinolaryngology, University of Toyama, and was diagnosed as having ocular flutter (OF). Electronystagmography (ENG), 30 days after the onset revealed loss of visual suppression in both ears. She was followed up without treatment, and after about 60 days, the OF disappeared, and 4 months later, it had completely resolved.

It was speculated that there was a disorder in the cerebellar vermal lobules VI and VII and temporary flocculus and nodulus disorders.

Dizziness or vertigo caused by disorders of the central nervous system may be associated with characteristic eye movement abnormalities. One of the diseases that is associated with characteristic eye movement abnormalities is medial longitudinal fasciculus (MLF) syndrome, which is caused by disorder of the MLF.

A 75-year-old woman presented with a two-day history of dizziness developing upon head movement. She was suspected as having benign paroxysmal positional vertigo and was referred to our department. Although the Dix–Hallpike and roll tests failed to induce nystagmus, the horizontal gaze nystagmus test revealed adduction paralysis of both eyes and nystagmus in the bilateral abducted eyes. Diffusion-weighted MRI images revealed high-signal intensities in the left thalamus, right hippocampus, and midbrain. She was diagnosed as having bilateral MLF syndrome, associated with multiple cerebral infarctions. She was hospitalized and received anticoagulation, cerebral protection, anti-edema therapy, and rehabilitation. No cerebrovascular abnormalities or embolic sources were observed on cerebral angiography, carotid ultrasonography, or echocardiography. Because serologic examination revealed a positive result for lupus anticoagulant (LA), antiphospholipid antibody syndrome (APS) was suspected. On the ninth hospitalization day, she was able to perform activities of daily living. She was discharged on the tenth day of hospitalization.

Five months post-treatment, she was definitively diagnosed as having APS because of persistently positive serology for LA. The eye movement abnormalities observed at the initial examination had disappeared. After three years of warfarin treatment, no recurrence was observed.

Since central vertigo may be included among cases referred to the department of otorhinolaryngology with suspected peripheral vertigo, the role of the otorhinolaryngologist is significant not only in the diagnosis of peripheral vertigo but also in the diagnosis of central disease.

We report a rare case of a postoperative ear in which the mastoid cavity was obliterated with acryl resin.

A 70-year-old male patient presented to our hospital with a history of right ear discharge. He had undergone tympanoplasty about 60 years ago, but further details of the surgery were unknown. His hearing worsened after the surgery, but he had had no ear discharge and been asymptomatic until now. He came to our hospital with several months’ history of ear discharge. We suspected recurrence of cholesteatoma and preoperative temporal bone CT showed a shadow with linear edges in the right mastoid cavity. Reoperation was performed for suspected recurrence of cholesteatoma. At mastoidectomy, a clear synthetic resin-like material was found to be obliterating the mastoid cavity from the aditus ad antrum to the digastric ridge. The obliterating material was determined to be polymethyl methacrylate (PMMA), which is an acrylic resin by the Chemicals Evaluation and Research Institute.

The use of PMMA, which has no tissue affinity, as an obliterating material for the mastoid cavity has been reported in foreign literature, but is extremely rare in Japan.

Endoscopic partial resection of the nasal septum (EPRN) is one of the approaches for septoplasty. The incision is made approximately 8 mm caudal to the junction of the septal cartilage and lamina perpendicularis of the ethmoid bone. EPRN contributes to widening of the middle meatus of the nose through resection of the tilting lamina perpendicularis of the ethmoid bone. We performed EPRN in 30 cases between January 2016 and December 2021. We investigated the relationship between the direction of tilt of the lamina perpendicularis of the ethmoid bone and direction of deviation of the caudal end. The degree of caudal end deviation was investigated by analyzing the CT data. The proportion of cases with “no deviation” of the caudal end was 23% (7/30) and the proportion of cases with “mild deviation” of the caudal end was 77% (23/30). In the 23 cases with “mild deviation,” we examined the relationship between the direction of tilt of the lamina perpendicularis of the ethmoid bone and direction of deviation of the caudal end. We defined cases in which both the laminar tilt and deviation of the caudal end occurred in the same direction as the “C type” and those in which they occurred in opposite directions as the “S type”. In regard to the approach side in the “C type” patients (n = 11), the number of cases via the narrower nasal cavity was five and the number of cases via the wider nasal cavities was six. In regard to the approach side in “S type” patients (n = 12), all of them were operated via the wider nasal cavity. The overall operation time was 3–12 minutes (8 minutes), with no significant difference between the two groups. Of all the patients, one case of the “C type” who had been operated via a narrower nasal cavity developed nasal septal perforation.

We conclude that it is desirable to choose a wider nasal cavity as an approach for EPRN, irrespective of the direction of tilt of the lamina perpendicularis of the ethmoid bone.

Eosinophilic chronic rhinosinusitis (ECRS) is a recurrent disease that is often refractory to existing therapies. Dupilumab is indicated for the treatment of chronic rhinosinusitis with nasal polyps (CRSwNP).

We report three cases of ECRS that were treated with dupilumab. The patients were 46, 61, and 69 years old. All three patients were female and had severe asthma, and the polyps shrank with dupilumab treatment in all three patients. In one case, the polyps completely disappeared, whereas in the other two cases, residual polyps remained. The polyps in the patients with residual polyps showed a fuller, firmer, and more organic appearance, rather than the fresher appearance usually associated with nasal polyps. On the other hand, in the patient who showed complete disappearance of the polyps, the polyps were white, soft and fresh in appearance.

Our experience suggests that dupilumab may be more effective for fresh nasal polyps before fibrosis develops. In these cases, dupilumab improves the olfactory disturbance, whereas in others, the olfactory disturbance persists even if the nasal polyps shrink in size, suggesting that dupilumab alone may not be effective against conductive olfactory disturbances in patients with CRSwNP.

Although no obvious side effects were observed in any of the three patients in this report, there have been previous reports of serious side effects associated with dupilumab, and careful observation is recommended during dupilumab treatment.

Distant metastases from breast cancer are not uncommon, however, spread to the paranasal sinuses is fairly rare. Herein, we report a case of ethmoid sinus metastasis from breast cancer. A 74-year-old woman presented with diplopia 10 months after a right mastectomy for breast cancer. Subsequently, the symptoms of visual impairment, vomiting, headache and generalized fatigue appeared rapidly. She was referred to our department a month after the onset. CT examination revealed lesions in the right ethmoid sinus and orbital apex, with osteolysis of the medial orbital wall and skull base. MRI examination revealed a right ethmoid lesion which was visualized as a high intensity of T2-weighted images and as a low intensity on T1-weighted images. The findings were suggestive of malignant tumor of the right ethmoid sinus, and we performed endoscopic sinus surgery under general anesthesia. The right ethmoid sinus was filled with fragile tissue and the lamina papyracea was partially destroyed. The histological diagnosis made from a biopsy specimen was triple-negative invasive ductal carcinoma. Whole-body CT examination revealed metastases to the axillary lymph nodes, mediastinal lymph nodes, pleura, and both lungs. Her general condition deteriorated, she refused further therapy, and she died 4 months after the onset.

According to previous case reports of breast cancer metastasis to the paranasal sinuses, diplopia, proptosis, and visual impairment are the most frequent symptoms. These symptoms resemble those of invasive fungal rhinosinusitis, and for differential diagnosis, MRI and histological examination are useful. Otolaryngologists need to consider paranasal sinuses and the orbit as potential sites of metastasis from breast cancer.

We report a case that presented with a swelling in the lower part of the auricle that was initially suspected as a parotid tumor, but was eventually diagnosed as cat scratch disease (CSD).

A 66-year-old man presented with fever and a swollen mass in the lower part of the auricle. The patient was initially treated for parotitis, however, as the condition did not improve with the treatment, the patient was referred to our hospital.

On initial examination, the patient was found to have a prominent swollen mass with mild tenderness in the lower part of the auricle, and high fever (38°C). Blood samples showed a mild inflammatory reaction with a WBC count of 7700/μL and serum CRP of 5.8 mg/dL. Contrast-enhanced MRI revealed multiple abscesses within both the parotid glands. Fine needle aspiration cytology revealed a small amount of pus cells, but no bacteria were isolated on culture. Therefore, tuberculous lymphadenitis, Kikuchi disease, and CSD were considered in the differential diagnoses, and various examinations were performed for a definitive diagnosis. Finally, the diagnosis of cat scratch disease was confirmed by positive serology for IgM and IgG antibodies against Bartonella. The patient was treated with azithromycin, and remission was achieved about 27 weeks after the initial visit.

In conclusion, although it commonly presents with lymphadenopathy at the site of injury, CSD should be considered in the differential diagnosis even when abscess formation is observed in the parotid gland, as in the current case.

Granulocyte colony stimulating factor (G-CSF)-producing parotid carcinoma is a rarely encountered disease, and is reported to carry an extremely poor prognosis. We report the case of an 82-year-old woman who was diagnosed as having a G-CSF-producing parotid carcinoma and showed a long survival.

She complained of rapid swelling and pain in the area of the parotid gland on the left side. Aspiration cytology from the left parotid gland was suggestive of malignancy (class V). Specimens from the self-crushing site of the skin were histopathologically diagnosed as poorly differentiated adenocarcinoma. Blood examination showed a marked increase in the peripheral blood WBC count and serum G-CSF level. To completely resect the tumor, extended total parotidectomy and neck dissection were performed on the left side, followed by additional radiotherapy at a total dose of 60 Gy. Postoperative histopathology revealed poorly differentiated adenocarcinoma that showed positive immunostaining for G-CSF. The peripheral blood WBC count decreased rapidly and the serum G-CSF level normalized after the surgery. No recurrence after the surgery has been observed for 4 years and 7 months. For G-CSF-producing tumors, surgery is thought to be the only effective treatment, with limited effectiveness of chemotherapy and radiation therapy. Complete resection of the tumor was considered as one of the reasons for the long-term survival.

Solitary plasmacytoma occurs in the soft tissues in about 2%–5% of cases, but in about 60% of these cases, they occur in the head and neck region, so that they are often seen by otorhinolaryngologists. However, reports of solitary plasmacytoma arising from the tongue are so few, that they are rarely listed in the differential diagnosis of tongue tumors. Herein, we report a case of solitary plasmacytoma of the tongue.

The patient was a 44-year-old woman who presented with a white lesion on the left edge of tongue that she had first noticed 10 years earlier. She was diagnosed as having lichen planus by a dentist and treated conservatively. However, as the lesion became painful, she was referred to our department. A 12 × 10 mm lesion with erosion on the surface was observed on the left edge of the tongue, and the findings of biopsy led to the suspicion of plasmacytoma. Contrast-enhanced CT and MRI scan showed a slightly enhancing lesion. No cervical lymphadenopathy was observed. The lesion was excised with a safety margin under general anesthesia, and histopathology confirmed the diagnosis of plasmacytoma. Blood and urine tests showed no evidence of organ or tissue impairment, and serum M protein and urinary Bence-Jones protein were negative. Bone marrow examination showed no atypical cells. FDG-PET/CT showed no obvious abnormal accumulation. Based on these findings, multiple myeloma was ruled out and the patient was diagnosed as having solitary plasmacytoma of the tongue. We have followed her with no additional treatment and have not seen any evidence of recurrence or progression to multiple myeloma for 3 years after the surgery. However, even if solitary plasmacytoma could be controlled locally, progression to multiple myeloma is difficult to predict. Therefore, patients with solitary plasmacytoma require careful follow-up after local treatment.

Immune checkpoint inhibitors (ICIs) have been approved for the treatment of recurrent/metastatic head and neck cancer, expanding the range of treatment strategies. On the other hand, immune-related adverse events (irAEs) are known to occur with ICI therapy, and a small number of adverse events related to the nervous system are also known. We report a case of encephalitis and pneumonia caused by ICIs in a patient with nasopharyngeal cancer.

A 79-year-old man developed fever, impaired consciousness, and myoclonus after pembrolizumab therapy for nasopharyngeal cancer. After comprehensive examination, he was diagnosed as having pembrolizumab-induced autoimmune encephalitis and pneumonia and started on treatment with prednisolone (120 mg/day). The symptoms improved transiently with the treatment, but recurred when the dose of prednisolone was gradually reduced to 15 mg/day. The dose of prednisolone was therefore increased again to 60 mg/day and tapered, and finally, it was possible to prevent relapse at a maintenance dose of 20 mg/day.

The frequency of irAEs is expected to increase due to the expanded indications of ICIs, and in patients with suspected irAEs, appropriate diagnosis and management through comprehensive multidisciplinary consultation are important.

Background: Tumors of the lacrimal sac are relatively rare. The initial symptoms are non-specific, including excessive lacrimation and swelling of the lacrimal region, so that these tumors are often diagnosed at a late stage. There are various histological types of lacrimal sac tumors, but there have been only few reports of primary malignant tumors of the lacrimal sac equivalent to salivary duct carcinoma.

Case: We report the case of a 61-year-old male patient with a malignant tumor of the lacrimal sac. He was treated by tumor resection with orbital exenteration, removal of a part of the maxilla, neck dissection, and reconstruction with a right scapular skin flap.

Consideration: Although complete surgical removal is preferred, multidisciplinary treatment, including radiotherapy and chemotherapy, should be considered, depending on the histological type and results of immunostaining. Since there are reported cases of metastasis and recurrence of lacrimal sac tumors even after 10 years, careful long-term follow-up is necessary.

Conclusions: In this report, we present a rare case of primary malignant tumor of the lacrimal sac equivalent to salivary duct carcinoma. We need to consider multidisciplinary treatment for these tumors, depending on the histology and degree of progression.

Anatomy education is a very important part of the curriculum for medical students and is also essential for surgeons to perform safe surgery. The anatomy of the sinus cavity is complicated and not easy to understand through dissection practice of cadavers and reading of textbooks of surgical anatomy. Developing methods to effectively teach the anatomy of structures with a complex anatomy is essential for safe medical procedures.

We devised a system to observe the paranasal sinuses in virtual reality (VR) space by polygonizing the shape of the sinus cavity from sinus CT images. Medical students moved around in the VR space and observed the sinuses from various angles that is not possible in a conventional anatomy lab. This VR application was applied to student education to investigate whether it could contribute to the understanding and learning of the complex anatomy of the sinuses. A questionnaire was administered to 27 medical students (15 males and 12 females; mean age, 24.9 years) to evaluate their understanding of sinus anatomy and the number of times they had experienced and used VR systems.

It was found that more than 70% of the students had never used VR before, but they could use it smoothly even if they were unfamiliar with the operation of VR systems, and the learning process was enjoyable and efficient. Thus, VR applications could be a useful tool for the education of medical students.