Olfactory neuroblastoma is a rare disease, and reports about late complications are scarce. We experienced a case in which meningitis and panhypopituitarism developed in the late period after Proton beam therapy for Olfactory neuroblastoma. Herein, we report our experience with this case in context of the current literature.

A female in her eighties had undergone Endoscopic Sinus Surgery on the right side 10 years ago. She was diagnosed with Olfactory neuroblastoma and had undergone Proton beam therapy. One week ago, she complained of a headache and was treated for acute sinusitis. However, she experienced consciousness disorder four days ago, and was admitted to another hospital with the diagnosis of meningitis. She was treated with an antibacterial agent but her symptom did not improve. Therefore, the patient was transferred to our hospital to undergo Endoscopic Sinus Surgery for a therapeutic diagnosis. Her consciousness quickly improved on postoperative day 1. Moreover, she developed central diabetes insipidus due to panhypopituitarism, which we considered was induced as a side effect of Proton beam therapy. While there are few reports about late complications of Proton beam therapy for Olfactory neuroblastoma, Proton beam therapy has recently been covered by insurance, and we are concerned that the number of late complications of Proton beam therapy will increase. It is necessary to explain the potential complications to patients and observe them for a long time.

Cerebrospinal fluid (CSF) rhinorrhoea occurs due to breakdown of the structure that separates the airways from the subarachnoid space. Most cases of CSF leak will recover with surgical treatment. The current case of refractory nasal CSF leakage was able to be closed by endoscopic intranasal repositioning. The patient presented with recurrent CSF rhinorrhoea after endoscopic surgery. He exhibited watery rhinorrhoea. In nasal endoscopic findings, a clear watery nasal discharge was found, but the fistula site could not be identified. Sternberg’s canal was presumed as the site of the fistula by CT scans. Endoscopic intranasal repositioning was performed again, and the patient has since recovered without recurrence.

Treatment of CSF leakage requires accurate identification of the fistula, and it is necessary to keep the fistula site under clear vision with a secure surgical approach, as much as possible. After the endoscopic modified medial maxillectomy approach, the medial wall of the maxillary sinus was opened widely with preservation of the nasolacrimal duct. Additionally, the pterygopalatine fossa approach was used. Therefore, a good surgical site to reach the fistula outside the sphenoid bone was secured. The patient had no further symptoms of nasolacrimal duct, and had a good postoperative course.

The WHO classification of salivary gland tumors was revised in 2017, and Mammary analogue secretory carcinoma (MASC) was classified for the first time. We experienced 3 cases that were diagnosed as MASC in the parotid after tumor extraction operation. None of them were diagnosed as malignant tumors based upon fine needle aspiration. Pathological investigations on the resected specimens showed ETV6-NTRK3 fusion gene by genetic testing, and they were diagnosed as MASC. One of them exhibited partial extrusion, and it was considered that the grade had changed to severe stage. None of the cases exhibited any post-operative recurrence.

We considered the pathological and clinical features of MASC through these 3 cases, and report our experiences, herein.

Oncocytoma is considered to be a neoplastic proliferation of oncocytes, and are multicentric in the ducts, striatum, intervening and tufts of normal human glandular tissue. When oncocytoma undergoes malignant transformation, it is referred to as oncocytic carcinoma, and the frequency of occurrence has been reported to be about 16%. In principle, resection is desirable for treatment, and even in the case of follow-up, surgical treatment is required for cases with pain or rapid growth because malignant transformation of the tumor is suspected.

The patient was an 86-year-old, female who was diagnosed with a mass in the lower left jaw. She exhibited neoplastic lesions in the left submandibular and parotid glands, and underwent left submandibular gland tumor resection for the left submandibular gland tumor. She was subsequently diagnosed with oncocytoma. As she had a history of heart disease and was at risk of general anesthesia, she was followed up forbthe left parotid tumor, but it gradually increased and became painful, so she left ear 5 years later. After resection of the parotid tumor, she was diagnosed as having mucoepidermoid carcinoma based on the pathological results. No recurrence has been observed 1 year after the operation.

When multiple cervical tumors are found, even if one of them has been diagnosed as oncocytoma, early surgery is desirable, considering that the other tumors could be of different types or malignant.

Even in the case of simple follow-up, strict follow-up is required, always considering the possibility of malignancy.