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Background: The ventriculus terminalis (VT) is a cystic embryological remnant of the conus medullaris that usually regresses after birth. This structure rarely persists into adulthood and may produce neurological symptoms. We recently encountered three cases of symptomatic enlarging VT. Case Description: The three female patients were 78, 64, and 67 years old. Symptoms included pain, numbness, motor weakness, and frequent urination that gradually worsened. Magnetic resonance imaging revealed cystic dilatations of slow growing VT. These patients showed marked improvement after cyst-subarachnoid shunt using a syringo-subarachnoid shunt tube. Conclusion: Symptomatic enlarging VT is an extremely rare cause of conus medullaris syndrome and the optimal treatment strategy remains unclear. Surgical management may thus be appropriate for patients with symptomatic enlarging VT.

Background: Intravascular large B-cell lymphoma (IVLBCL) is a rare entity among large B-cell non-Hodgkin lymphomas and is often difficult to diagnose. We report the case of a patient with IVLBCL who presented with central nervous system (CNS) symptoms alone, in which positron emission tomography (PET) enabled a rapid and accurate diagnosis. Case Description: An 81-year-old woman was admitted to our hospital with a 3-month history of gradually progressive dementia and declining spontaneity. Magnetic resonance imaging revealed multiple hyperintense lesions bilaterally on diffusion-weighted imaging without enhancement on gadolinium-enhanced T1-weighted imaging. Laboratory findings showed elevated serum lactate dehydrogenase (626 U/L) and soluble interleukin-2 receptor (sIL-2R) (4692 U/mL). Cerebrospinal fluid (CSF) analysis showed slightly elevated levels of protein (166 mg/dL) and lymphocytic cells (29/μL), and β2-microglobulin (β2-MG) (4.6 mg/L) was highly elevated. Whole-body computed tomography revealed faint ground-glass opacities in the upper and middle lung fields and diffuse enlargement of both kidneys without lymph node swelling. 18F-fluorodeoxyglucose (FDG)-PET showed diffuse and remarkably high FDG uptake in both upper lungs and kidneys without uptake by lymph nodes, suggesting a malignant hematological disease. IVLBCL was confirmed histologically by incisional random skin biopsy from the abdomen. Chemotherapy using R-CHOP regimen in combination with intrathecal methotrexate injection was started on day 5 after admission and follow-up neuroimaging showed no signs of recurrence. Conclusion: IVLBCL presenting with CNS symptoms alone is rare and often has a poor prognosis associated with delayed diagnosis, and various evaluations (including systemic analysis) are therefore necessary for early diagnosis. FDG-PET, in addition to identification of clinical symptoms and evaluation of serum sIL-2R and CSF β2-MG, enables rapid therapeutic intervention in IVLBCL presenting with CNS symptoms.

Background: Epithelioid glioblastoma is a rare aggressive variant of glioblastoma multiforme (GBM), which was formally recognized by the World Health Organization classification of the central nervous system in 2016. Clinically, epithelioid GBMs are characterized by aggressive features, such as metastases and cerebrospinal fluid dissemination, and an extremely poor prognosis. A rare case of epithelioid GBM that was discovered as a multicentric glioma with different histopathology is reported. Case Description: A 78-year-old man was admitted to our hospital with mild motor weakness of the right leg. Neuroimaging showed small masses in the left frontal and parietal lobes on magnetic resonance imaging. The abnormal lesion had been increasing rapidly for 3 weeks, and a new lesion appeared in the frontal lobe. 11C-methionine positron emission tomography (PET) showed abnormal uptake corresponding to the lesion. To reach a definitive diagnosis, surgical excision of the right frontal mass lesion was performed. Histological findings showed diffuse astrocytoma. Only radiotherapy was planned, but the left frontal and parietal tumors progressed further within a short period. Therefore, it was thought that these tumors were GBM, and a biopsy of the left parietal tumor was performed. The histological diagnosis was epithelioid GBM. Immunohistochemistry showed that most tumor cells were negatively stained for p53 and isocitrate dehydrogenase 1. BRAF V600E mutations were not identified, but TERT promoter mutations were identified. Immediately after surgery, the patient was given chemotherapy using temozolomide, extended local radiotherapy and then bevacizumab. After 6 months, he showed no signs of recurrence. Conclusion: Epithelioid GBM is one of the rarest morphologic subtypes of GBM and has a strongly infiltrative and aggressive nature. Therefore, careful identification of preoperative imaging studies and detailed evaluation of genetic studies are necessary to select the appropriate treatment for epithelioid GBM.

Background: Onyx has already been reported as an effective and safe agent in transarterial embolization of cranial dural arteriovenous fistula (d-AVF). However, successful treatment is related to not only complete shunt obliteration but also preservation of a normal route of venous drainage. Here, we present a case of transverse sigmoid d-AVF in which successful treatment was achieved by transarterial Onyx embolization with targeted balloon protection of the venous drainage. Case Description: A 70-year-old man presented with a 3-month history of tinnitus in the left ear and mild headache. Magnetic resonance imaging (MRI) showed a cluster of abnormal blood vessels in the area of the left transverse sinus (TS)-sigmoid sinus (SS) junction. Cerebral angiography demonstrated a Cognard type IIa d-AVF at the left TS-SS junction, supplied mainly by vessels such as the left middle meningeal artery, left occipital artery, and left meningohypophyseal trunk. In the venous phase, the ipsilateral TS-SS was recognized as a functional sinus and the left vein of Labbe drained into the TS near the drainage channel. Based on these findings, we decided to perform endovascular treatment under a transarterial approach with Onyx using targeted balloon protection of the venous sinus to protect against Onyx migration and preserve antegrade sinus flow. The patient recovered well without sequelae, and follow-up MRI 12 months later showed complete disappearance of the d-AVF. Conclusion: This treatment strategy using targeted balloon protection may be very useful to preserve antegrade sinus flow in patients with Cognard type IIa d-AVF.

Background: Sarcoidosis is a multisystem disorder characterized by noncaseating epithelioid granulomas. However, neurosarcoidosis occurring only in the medulla oblongata is very rare and lacks specific imaging and clinical features. We report a rare case of neurosarcoidosis arising from the medulla oblongata alone, suggesting the significance of pathological findings for accurate diagnosis. Case Description: A 78-year-old woman with a history of rheumatoid arthritis was admitted to our hospital with a 3-month history of progressive numbness in bilateral lower extremities and gait disturbance. Neurological examination on admission showed mild bilateral paired paralysis of the lower limbs (manual muscle test: right 2/V; left 4/V) and marked numbness in the right lower limb. Neuroimaging revealed a solid mass with clear boundaries in the dorsal medulla oblongata appearing hypointense on T1-weighted imaging (WI), hyperintense on T2-WI, and hypointense on diffusion WI (DWI), with strong enhancement on gadolinium-enhanced T1-WI. Cerebrospinal fluid analysis showed moderately elevated levels of protein and lymphocytic cells. Biopsy to determine the exact diagnosis revealed histological findings of noncaseating epithelioid granulomas and inflammatory infiltration, consistent with sarcoidosis. Postoperatively, corticosteroid therapy with prednisolone was initiated as soon as possible, resulting in marked reductions in lesion size. Follow-up neuroimaging after 12 months showed no signs of recurrence. Conclusion: Neurosarcoidosis is difficult to diagnose from routine neuroimaging and laboratory findings. Accurate diagnosis requires careful identification of clinical signs, hypointensity on DWI, and morphological findings from surgical biopsy.

Background: The findings of a hyperintense sign on T2-weighted imaging (T2-WI) and gadolinium (Gd) contrast enhancement on magnetic resonance imaging (MRI) of the brain stem suggest malignant glioma. However, this pathological condition is probably uncommon, and it may be unknown that a dural arteriovenous fistula (DAVF) can imitate this radiological pattern. In addition, it is extremely rare to be caused by a spinal DAVF. Here, a rare case of spinal DAVF that mimicked malignant glioma of the medulla oblongata is presented. Case Description: A 56-year-old woman was admitted with a progressive gait disturbance, vertigo, and dysphasia. MRI showed a hyperintense signal in the medulla oblongata on fluid-attenuated inversion recovery (FLAIR) and moderate contrast enhancement on Gd-enhanced MRI. Interestingly, Gd-enhanced MRI demonstrated abnormal dilated veins around the brain stem and cervical spinal cord. Cerebral angiography showed spinal DAVF at the left C4/C5 vertebral foramen fed by the C5 radicular artery. The fistula drained into spinal perimedullary veins and flowed out retrograde at the cortical vein of the posterior cranial fossa. Therefore, surgical disconnection of the spinal DAVF was performed by a posterior approach. The patient’s postoperative course was uneventful. Cerebral angiography showed complete disappearance of the DAVF, with marked reductions of the hyperintense sign of the medulla oblongata on FLAIR. Conclusion: This important case illustrates MRI findings mimicking brain stem glioma. In cases with the hyperintense sign-on T2-WI associated with contrast enhancement suspicious of brainstem glioma, careful checking for perimedullary abnormal vessels and additional cerebral angiography should be performed.

Background: Granular cell tumor (GCT) of the sellar region is a rare tumor of the sellar and suprasellar regions that originate from the neurohypophysis. This tumor is very difficult to differentiate from other pituitary neoplasms, such as pituitary adenoma, pituicytoma, and spindle cell oncocytoma. We report a rare case of GCT arising from the posterior pituitary of the sellar region and suggest a useful indicator for accurate diagnosis and pitfalls for surgical procedures. Case Description: A 42-year-old woman was admitted to our hospital with bitemporal hemianopsia. Neuroimaging showed a large pituitary tumor in the sellar and suprasellar regions with a hypointense part on T2-weighted magnetic resonance imaging, and the enhanced anterior pituitary gland was displaced anteriorly. Laboratory findings showed mild hyperprolactinemia. Subtotal resection of the tumor was achieved using an endoscopic endonasal transsphenoidal approach. Histological findings showed round or polygonal cells with abundant granular eosinophilic cytoplasm staining strongly for thyroid transcription factor 1. The tumor was, therefore, diagnosed as a GCT of the sellar region, belonging to tumors of the posterior pituitary. After surgery, visual impairment and anterior pituitary function were improved. Follow-up neuroimaging after 1 year showed no signs of recurrence. Conclusion: GCT of the sellar region is difficult to diagnose on routine neuroimaging. Therefore, accurate diagnosis requires careful identification of clinical signs, magnetic resonance imaging including hypointensity on T2-weighted imaging, and analysis of combined morphological and immunohistochemical studies.

Background Chordoid glioma of the third ventricle is a rare neuroepithelial tumor characterized by a unique histomorphology within the third ventricular region, but with radiological and histopathological features mimicking benign lesions such as meningioma. We report a case of chordoid glioma of the third ventricle and suggest a useful indicator for accurate diagnosis. Case description A previously healthy 46-year-old woman was admitted to our hospital with mild headache. Neuroimaging revealed a large tumor measuring approximately 18 mm in the suprasellar region, and perifocal edema in the optic tract and internal capsule on magnetic resonance imaging. Laboratory findings revealed no pituitary dysfunction including diabetes insipidus. Gross total resection of the tumor was performed by the interhemispheric translamina terminalis approach. Histological findings revealed nests of regular epithelioid cells with large nuclei and abundant eosinophilic cytoplasm within myxoid stroma. Immunohistochemical studies demonstrated diffuse cytoplasmic expression of glial fibrillary acidic protein (GFAP) and CD34, and strong nuclear staining for thyroid transcription factor 1 (TTF-1). We, therefore, histologically classified the tumor as chordoid glioma of the third ventricle. Headache improved immediately postoperatively, and follow-up neuroimaging after 12 months showed no signs of recurrence. Conclusions Chordoid glioma of the third ventricle is a very rare tumor that is difficult to diagnose on routine neuroimaging. Accurate diagnosis requires detailed analysis of neuroimaging and immunohistochemical studies using CD34 and TTF-1 staining.