Magnetic resonance imaging (MRI) is an indispensable tool in neurosurgery, though it sometimes faces challenges such as \"tumor mimicry.\" While intraoperative MRI (iMRI) is widely recognized for its usefulness in achieving maximal safe resection during glioma surgery, instances of tumor mimicry still occur on iMRI. Moreover, reports on tumor mimics observed through iMRI, particularly in low-grade gliomas, remain scarce. In this article, we present a case of oligodendroglioma, where a newly emerged T2 high-signal intensity region on iMRI necessitated differentiation from tumor expansion. A 23-year-old man presented with a newly diagnosed brain tumor and underwent surgical removal. An iMRI taken after tumor removal revealed a newly emerged T2 hyperintense area without diffusion restriction around the resection cavity, which was not observed in the preoperative MRI. Suspecting residual tumor, we performed additional resection. An MRI on the following day confirmed that the T2 hyperintense area identified on the iMRI had been completely resected but also revealed an enlarged T2 high-signal area over a wider region. Histopathology found no tumor cells in the additionally resected area, indicating that the iMRI finding was a tumor mimic. Six months later, the T2 high-signal area around the resection cavity had disappeared on MRI without any additional treatment. This case highlights the challenge of distinguishing between T2 hyperintense mimicry and tumor enlargement during glioma surgery seen on iMRI. Despite the significant value of iMRI, our report underscores the need for careful interpretation in neurosurgical practice, particularly with non-contrast-enhancing tumors.

UNASSIGNED: Although awake surgery is the gold standard for resecting brain tumors in eloquent regions, patients with hearing impairment require special consideration during intraoperative tasks.
UNASSIGNED: We present a case of awake surgery using sign language in a 45-year-old right-handed native male patient with hearing impairment and a neoplastic lesion in the left frontal lobe, pars triangularis (suspected to be a low-grade glioma). The patient primarily communicated through sign language and writing but was able to speak at a sufficiently audible level through childhood training. Although the patient remained asymptomatic, the tumors gradually grew in size. Awake surgery was performed for tumors resection. After the craniotomy, the patient was awake, and brain function mapping was performed using tasks such as counting, picture naming, and reading. A sign language-proficient nurse facilitated communication using sign language and the patient vocally responded. Intraoperative tasks proceeded smoothly without speech arrest or verbal comprehension difficulties during electrical stimulation of the tumor-adjacent areas. Gross total tumor resection was achieved, and the patient exhibited no apparent complications. Pathological examination revealed a World Health Organization grade II oligodendroglioma with an isocitrate dehydrogenase one mutant and 1p 19q codeletion.
UNASSIGNED: Since the patient in this case had no dysphonia due to training from childhood, the task was presented in sign language, and the patient responded vocally, which enabled a safe operation. Regarding awake surgery in patients with hearing impairment, safe tumor resection can be achieved by performing intraoperative tasks depending on the degree of hearing impairment and dysphonia.

Pilocytic astrocytomas (PA) are the most common gliomas in children/adolescents but are less common and poorly studied in adults. Here, we describe the clinical presentation, surgical management, and outcomes of surgically treated adult patients with intraventricular (IV) PA and review the literature.
Consecutive adult patients treated for IV brain tumors at a tertiary academic center over 25 years (1997-2023) were identified. Clinical data were reviewed retrospectively for adult IV PA patients. A systematic literature review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.
Eight patients with IV PA were included. Median age was 25 years (range, 18-69 years), and 4 (50%) were female. The most common tumor location was the lateral ventricle (5, 63%), followed by the fourth ventricle (3, 37%). Subtotal and near total resection were the most common surgical outcomes (6 patients, 75%), followed by gross total resection in 2 (25%). Progression or recurrence occurred in 3 patients (37%), requiring repeat resection in 2 patients. The 5-year overall survival and progression-free survival were 67% and 40%, respectively. In addition, 42 cases were identified in the literature.
PAs in adults are rare and an IV location is even more uncommon. The findings demonstrate the challenges in caring for these patients, with overall- and progression-free survival outcomes being poorer than the general adult PA population. Findings support the employment of surgical techniques and approaches that favor gross total resection when possible. Further studies are needed to better characterize this unique presentation.

UNASSIGNED: Mature cystic teratoma (MCT) is a common type of ovarian tumors that can, in rare cases, undergo malignant transformation. It has been discovered that MCT patients may experience psychiatric symptoms due to the presence of anti-N-methyl-D-aspartate receptor (NMDAR) antibodies, which is the underlying cause of autoimmune encephalitis. Here, we present the first documented case of a patient with anti-NMDAR encephalitis who also had a morphology of low-grade glioma within MCT.
UNASSIGNED: A 45-year-old woman presented with seizures, altered consciousness, abnormal NMDAR antibody IgG titers, and abnormal brain MRI findings confirm the diagnosis of anti-NMDAR encephalitis. Physical examination revealed an oval mixed echo mass measuring 54 × 37 mm in the left adnexal area on ultrasound of the uterine appendage. The patient underwent laparoscopic left ovarian and fallopian tube resection. The pathological gross examination revealed a pile of grayish-red cystic and solid fragmented tissue measuring 7 × 6 × 2.2 cm. Histological examination revealed characteristic components of MCT. Furthermore, the solid component of the gross tissue showed proliferative and densely arranged astrocytes with cellular atypia, which were positive for GFAP and Olig-2, negative for IDH1 and EMA. And the Ki67 index was approximately 10%, suggesting the presence of low-grade glioma lesions. The patient was diagnosed with malignant transformation of MCT into a morphology of low-grade glioma, not otherwise specified. After the removal of the ovarian tumor, the patient\'s psychiatric symptoms improved.
UNASSIGNED: Low-grade glioma within MCT is a rare occurrence, and the presence of this malignant transformation in patients with anti-NMDAR encephalitis is even more uncommon.

BACKGROUND: Laser interstitial thermal therapy (LITT) has emerged as a minimally invasive treatment modality for ablation of low-grade glioma (LGG) and radiation necrosis (RN).
OBJECTIVE: To evaluate the efficacy, safety, and survival outcomes of patients with radiographically presumed recurrent or newly diagnosed LGG and RN treated with LITT.
METHODS: The neuro-oncological database of a quaternary center was reviewed for all patients who underwent LITT for management of LGG between 1 January 2013 and 31 December 2020. Clinical data including demographics, lesion characteristics, and clinical and radiographic outcomes were collected. Kaplan-Meier analyses comprised overall survival (OS) and progression-free survival (PFS).
RESULTS: Nine patients (7 men, 2 women; mean [SD] age 50 [16] years) were included. Patients underwent LITT at a mean (SD) of 11.6 (8.5) years after diagnosis. Two (22%) patients had new lesions on radiographic imaging without prior treatment. In the other 7 patients, all (78%) had surgical resection, 6 (67%) had intensity-modulated radiation therapy and chemotherapy, respectively, and 4 (44%) had stereotactic radiosurgery. Two (22%) patients had lesions that were wild-type IDH1 status. Volumetric assessment of preoperative T1-weighted contrast-enhancing and T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences yielded mean (SD) lesion volumes of 4.1 (6.5) cm3 and 26.7 (27.9) cm3, respectively. Three (33%) patients had evidence of radiographic progression after LITT. The pooled median (IQR) PFS for the cohort was 52 (56) months, median (IQR) OS after diagnosis was 183 (72) months, and median (IQR) OS after LITT was 52 (60) months. At the time of the study, 2 (22%) patients were deceased.
CONCLUSIONS: LITT is a safe and effective treatment option for management of LGG and RN, however, there may be increased risk of permanent complications with treatment of deep-seated subcortical lesions.

Polymorphous low-grade neuroepithelial tumor of the young (PLNTY), one of the pediatric-type diffuse low-grade gliomas, is characterized by a diffuse infiltrating pattern of oligodendroglioma-like tumor cells showing CD34 positivity and harbors mitogen-activated protein kinase (MAPK) alteration, such as vRAF murine sarcoma viral oncogene homolog B1 (BRAF) p.V600E or fibroblast growth factor fusion genetically. It occurs mainly in pediatric and adolescents with seizures due to the dominant location of the temporal lobe. However, there have been a few cases of PLNTY in adult patients, suggesting the wide range of this tumor spectrum. Here, we describe two cases of PLNTY, one in a 14-year-old female and the other in a 66-year-old female. The pediatric tumor showed typical clinical course and histopathology with BRAF p.V600E mutation, whereas the elderly tumor was unusual because of non-epileptic onset clinically and ependymal differentiation histopathologically harboring KIAA1549-BRAF fusion. There might be unusual but possible PLNTY, as in our elderly case. We also compared typical pediatric and unusual elderly tumors by reviewing the literature.

OBJECTIVE: Risk of cancer has been associated with body or organ size in several studies. We sought to investigate the relationship between intracranial volume (ICV) (as a proxy for lifetime maximum brain size) and risk of IDH-mutant low-grade glioma.
METHODS: In a multicenter case-control study based on population-based data, we included 154 patients with IDH-mutant WHO grade 2 glioma and 995 healthy controls. ICV in both groups was calculated from 3D MRI brain scans using an automated reverse brain mask method, and then compared using a binomial logistic regression model.
RESULTS: We found a non-linear association between ICV and risk of glioma with increasing risk above and below a threshold of 1394 ml (p < 0.001). After adjusting for ICV, sex was not a risk factor for glioma.
CONCLUSIONS: Intracranial volume may be a risk factor for IDH-mutant low-grade glioma, but the relationship seems to be non-linear with increased risk both above and below a threshold in intracranial volume.

Objective: Surgical approach to low-grade glioma (LGG) involving the posterior insula is challenging, especially in the left hemisphere, with a high risk of sensorimotor, language, or visual deterioration. In this study, a case series of 5 right-handed patients harboring a left posterior insular LGG is reported, by detailing a transcorticosubcortical approach. Method: The five surgeries were achieved in awake patients using cortical and axonal electrostimulation mapping. The glioma was removed through the left rolandic and/or parietal opercula, with preservation of the subcortical connectivity. Results: The cortical mapping was positive in the five patients, enabling the selection of an optimal transcortical approach, via the anterolateral supramarginal gyrus in four patients and/or via the lateral retrocentral gyrus in three cases (plus through the left superior temporal gyrus in one case). Moreover, the white matter tracts were identified in all cases, i.e., the lateral part of the superior longitudinal fasciculus (five cases), the arcuate fasciculus (four cases), the thalamocortical somatosensory pathways (four cases), the motor pathway (one case), the semantic pathway (three cases), and the optic tract (one case). Complete resection of the LGG was achieved in two patients and near-total resection in three patients. There were no postoperative permanent sensorimotor, language, or visual deficits. Conclusion: A transcortical approach through the parietorolandic operculum in awake patients represents safe and effective access to the left posterior insular LGG. Detection and preservation of the functional connectivity using direct electrostimulation of the white matter bundles are needed in this cross-road brain region to prevent otherwise predictable postsurgical impairments.

Infratentorial oligodendrogliomas, a rare pathological entity, are generally considered metastatic lesions from supratentorial primary tumors. Here, we report the case of a 23-year-old man presenting with a histopathologically confirmed right precentral gyrus grade 2 oligodendroglioma and a concurrent pontine grade 3 oligodendroglioma. The pontine lesion was biopsied approximately a year after the biopsy of the precentral lesion due to disease progression despite 4 cycles of procarbazine-CCNU-vincristine (PCV) chemotherapy and stable supratentorial disease. Histology and genetic analysis of the pontine biopsy were consistent with grade 3 oligodendroglioma, and comparison of the two lesions demonstrated common 1p/19q co-deletions and TERT promoter mutations but distinct IDH1 mutations, with a non-canonical IDH1 R132G mutation identified in the infratentorial lesion and a R132H mutation identified in the cortical lesion. Initiation of Temozolomide led to complete response of the supratentorial lesion and durable disease control, while Temozolomide with subsequent radiation therapy of 54 Gy in 30 fractions resulted in partial response of the pontine lesion. This case report supports possible distinct molecular pathogenesis in supratentorial and infratentorial oligodendrogliomas and raises questions about the role of different IDH1 mutant isoforms in explaining treatment resistance to different chemotherapy regimens. Importantly, this case suggests that biopsies of all radiographic lesions, when feasible and safe, should be considered in order to adequately guide management in multicentric oligodendrogliomas.

Pineal region pilocytic astrocytomas are extremely rare, and there is limited information about their radiological features. We report the case of a 22-year-old woman with a cystic lesion in the pineal region. In the 2 years after diagnosis, the lesion irregularly extended along the bilateral internal cerebral veins and the inferolateral surface of the corpus callosum. Gross total resection was achieved, and the histopathological study revealed that the lesion was a pilocytic astrocytoma. The lesion exhibited uncommon growth, leading to difficulty in establishing an accurate preoperative diagnosis. It should be noted that pineal region pilocytic astrocytomas can demonstrate atypical appearances.