Excessive Heat Generation by Power-driven Craniotomy Tools: A Possible Cause of Autologous Bone Flap Resorption Observed in an Ex Vivo Simulation

BACKGROUND

Bone flap resorption is an issue after autologous cranioplasty. Critical temperatures above 50°C generated by power-driven craniotomy tools may lead to thermal osteonecrosis, a possible factor in resorption. This ex vivo study examined whether the tools produced excessive heat resulting in bone flap resorption.

METHODS

Using swine scapulae maintained at body temperature, burr holes, straight and curved cuts, and wire-pass holes were made with power-driven craniotomy tools. Drilling was at the conventional feed rate (FR) plus irrigation (FR-I+), at a high FR plus irrigation (hFR-I+), and at high FR without irrigation (hFR-I-). The temperature in each trial was recorded by an infrared thermographic camera.

RESULTS

With FR-I+, the maximum temperature at the burr holes, the cuts, and the wire-pass holes was 69.0°C, 56.7°C, and 46.2°C, respectively. With hFR-I+, these temperatures were 53.1°C, 52.1°C, and 46.0°C, with hFR-I- they were 56.0°C, 66.5°C, and 50.0°C; hFR-I- burr hole- and cutting procedures resulted in the highest incidence of bone temperatures above 50°C followed by FR-I+, and hFR-I+. At the site of wire-pass holes, only hFR-I- drilling produced this temperature.

CONCLUSIONS

Except during prolonged procedures in thick bones, most drilling with irrigation did not reach the critical temperature. Drilling without irrigation risked generating the critical temperature. Knowing those characteristics may be a help to perform craniotomy with less thermal bone damage.

Trans-Sylvian and Transanterior Ascending Ramus Approach for Insular Gliomas at Zone I: 2-Dimensional Operative Video

Insular gliomas present significant challenges because of their deep-seated location and proximity to critical structures, including Sylvian veins, middle cerebral arteries, lenticulostriate arteries,1 long insular arteries,2 and functional cortices.3-6 The Berger-Sanai classification categorizes them into 4 zones (I-IV), providing a framework for understanding insular gliomas.7 The key factors for successful insular glioma removal are achieving the greatest insular exposure and surgical freedom.3 Given that the trans-Sylvian approach8,9 creates a narrow, linear surgical window,3 regardless of the zones, various surgical options have been employed, such as the trans-Sylvian approach with bridging vein cuts and the transcortical approach through functionally silent cortex.3,7,9-13 Dissecting sulci in glioma surgeries has proven beneficial.14-16 In this video publication, we dissected the anterior ascending ramus (AAR) and the Sylvian fissure, creating a triangular window instead of a linear one. A 74-year-old right-handed woman with a zone I insular glioma underwent a trans-Sylvian and trans-AAR approach, achieving total resection of the tumor without new neurological deficits. This approach provided maximum exposure of the insular region, offering a wide view from the anterior limiting sulcus to the anterior half of the superior limiting sulcus of the insula. The histological diagnosis revealed a rare adult pilocytic astrocytoma at the insula, documented in only one case report.17 The AAR,4 defined as a lateral sulcus (Sylvian fissure) branch,18 is present in 98.89% of hemispheres19; therefore, this surgical approach demonstrates broad applicability to zone I insular tumors. The patient provided consent for the procedure and the publication of her image under institutional review board approval (G23-08).

Distant recurrence in the cerebellar dentate nucleus through the dentato-rubro-thalamo-cortical pathway in supratentorial glioma cases

BACKGROUND

Distant recurrence can occur by infiltration along white matter tracts or dissemination through the cerebrospinal fluid (CSF). This study aimed to clarify the clinical features and mechanisms of recurrence in the dentate nucleus (DN) in patients with supratentorial gliomas. Based on the review of our patients, we verified the hypothesis that distant DN recurrence from a supratentorial lesion occurs through the dentato-rubro-thalamo-cortical (DRTC) pathway.

METHODS

A total of 380 patients with supratentorial astrocytoma, isocitrate dehydrogenase (IDH)-mutant (astrocytoma), oligodendroglioma, IDH mutant and 1p/19q-codeleted (oligodendroglioma), glioblastoma, IDH-wild type (GB), and thalamic diffuse midline glioma, H3 K27-altered (DMG), who underwent tumor resection at our department from 2009 to 2022 were included in this study. Recurrence patterns were reviewed. Additionally, clinical features and magnetic resonance imaging findings before treatment, at the appearance of an abnormal signal, and at further progression due to delayed diagnosis or after salvage treatment of cases with recurrence in the DN were reviewed.

RESULTS

Of the 380 patients, 8 (2.1%) had first recurrence in the DN, 3 were asymptomatic when abnormal signals appeared, and 5 were diagnosed within one month after the onset of symptoms. Recurrence in the DN developed in 8 (7.4%) of 108 cases of astrocytoma, GB, or DMG at the frontal lobe or thalamus, whereas no other histological types or sites showed recurrence in the DN. At the time of the appearance of abnormal signals, a diffuse lesion developed at the hilus of the DN. The patterns of further progression showed that the lesions extended to the superior cerebellar peduncle, tectum, tegmentum, red nucleus, thalamus, and internal capsule along the DRTC pathway.

CONCLUSION

Distant recurrence along the DRTC pathway is not rare in astrocytomas, GB, or DMG at the frontal lobe or thalamus. Recurrence in the DN developed as a result of the infiltration of tumor cells through the DRTC pathway, not dissemination through the CSF.

Angiographic evaluation of the distance from the top of the jugular bulb to the inferior petrosal sinus-internal jugular vein junction: simple classification and identification method for the orifice of the non-visualized inferior petrosal sinus during neuroendovascular surgery

BACKGROUND

The inferior petrosal sinus (IPS) is the transvenous access route for neurointerventional surgery that is occasionally undetectable on digital subtraction angiography (DSA) because of blockage by a clot or collapse. This study was aimed at analyzing the distance from the jugular bulb (JB) to the IPS-internal jugular vein (IJV) junction and proposing a new anatomical classification system for the IPS-IJV junction to identify the non-visualized IPS orifice.

METHODS

DSA of 708 IPSs of 375 consecutive patients were retrospectively investigated to calculate the distance from the top of the JB to the IPS-IJV junction, and a simple classification system based on this distance was proposed.

RESULTS

The median distance from the top of the JB to the IPS-IJV junction was 20.8 ± 14.7 mm. Based on the lower (10.9 mm) and upper (31.1 mm) quartiles, IPS-IJV junction variants were: type I, 0-10 mm (22.3%); type II, 11-30 mm (45.8%); type III, > 31 mm (23.9%); and type IV, no connection to the IJV (8.0%). Bilateral distances showed a positive interrelationship, with a correlation coefficient of 0.86. The bilateral symmetry type (visualized IPSs bilaterally) according to our classification occurred in 267 of 300 (89.0%) patients.

CONCLUSIONS

In this study, the IPS-IJV junction was located far from the JB (types II and III), with a higher probability (69.6%). This distance and the four-type classification demonstrated high degrees of homology with the contralateral side. These results would be useful for identifying the non-visualized IPS orifice.

Bilateral Trans-Sulcal and Interhemispheric Approaches for Butterfly Glioblastoma: 2-Dimensional Operative Video

Butterfly glioblastoma (bGB) poses significant surgical challenges, yet recent findings have highlighted the potential of surgical decompression in extending patient survival.1-10 The selection of a surgical strategy for bGB varies across studies. Generally, the side with a larger tumor volume is a preferred approach route, and the nondominant hemisphere is preferred when both tumors are similar in size. The contralateral tumor is removed via the resection cavity of the ipsilateral side,11 with successful utilization of endoscopic-assisted techniques.8 In the case of deep-seated bGB covered with a thick intact brain, accessing the tumor requires creating an invasive corridor, therefore minimizing the damage to the intact brain is ideal. A man in his 70s presented the new-onset seizure. Preoperatively, the patient exhibited a Karnofsky performance status of 50% without any motor deficits, and magnetic resonance imaging demonstrated a deep-seated anterior bGB with a larger tumor volume on the left dominant side. Imaging showed the tumor located just beneath the bilateral superior frontal sulci. Therefore we used these sulci to access the tumor with the minimum cut of the intact brain while preserving the frontal aslant tracts and used bilateral interhemispheric approaches to protect the cingulate bundles. We conducted the same technique for another deep-seated anterior bGB case, both resulting in postoperative Karnofsky performance status improvements (Video 1). Tailoring the surgical approach to the unique characteristics of each bGB case is important. The patients consented to the procedure and the publication of their images.

Frontotemporal craniotomy with skin incision along the superior temporal line outside the hairline in bald male patients with temporal gliomas

A head skin incision is inevitable in neurosurgical procedures and is usually concealed within the hairline. Androgenetic alopecia (AGA) is a progressive hair loss disorder or baldness highly prevalent in men. Therefore, if bald male patients require neurosurgical procedures, skin incisions cannot be concealed, but this subject is yet to be discussed in the literature. This study presents a frontotemporal craniotomy using a skin incision along the superior temporal line, ignoring the hairline in bald male patients. Thirty-three patients with temporal gliomas underwent surgical removal between 2015 and 2022. They were divided into three groups: bald male patients with skin incisions not concealed in the hairline (minimum group, n = 13), bald and non-bald male patients with skin incisions concealed in the hairline (male group, n = 11), and female patients with skin incisions concealed in the hairline (female group, n = 9). In the minimum group, patients had no complaints regarding the incision scar. Cosmetic outcome was excellent, and no cases showed surgical site infection or peripheral facial nerve palsy. Compared with the male and female groups, the minimum group had the shortest skin incision length; however, the craniotomy size and extent of resection were similar. Skin incision for frontotemporal craniotomy cannot be hidden in bald male patients, and the preferred location for the incision is unknown. The skin incision along the superior temporal line is a cosmetically favorable, feasible, and safe procedure.

[Glioblastoma, IDH-Wildtype]

The 5th edition of the WHO Classification of Central Nervous System Tumours(WHO2021)emphasizes the importance of molecular classification. A significant update was that glioblastoma IDH-mutant from WHO2016 was renamed and classified as astrocytoma IDH-mutant WHO grade 4 in WHO2021. This review describes the current updates to the glioblastoma classification, and discusses the essential knowledge regarding daily practice, especially for young neurosurgeons.

Randomized phase III study of high-dose methotrexate and whole-brain radiotherapy with/without temozolomide for newly diagnosed primary CNS lymphoma: JCOG1114C

BACKGROUND

The goal was to determine whether the addition of temozolomide (TMZ) to the standard treatment of high-dose methotrexate (HD-MTX) and whole-brain radiotherapy (WBRT) for primary central nervous system lymphoma (PCNSL) improves survival.

METHODS

An open-label, randomized, phase III trial was conducted in Japan, enrolling immunocompetent patients aged 20-70 years with histologically confirmed, newly diagnosed PCNSL. After administration of HD-MTX, patients were randomly assigned to receive WBRT (30 Gy) ± 10 Gy boost (arm A) or WBRT ± boost with concomitant and maintenance TMZ for two years (arm B). The primary endpoint was overall survival (OS).

RESULTS

Between September 29, 2014 and October 15, 2018, 134 patients were enrolled, of whom 122 were randomly assigned and analyzed. At the planned interim analysis, two-year OS was 86.8% (95% confidence interval [CI]: 72.5-94.0%) in arm A and 71.4% (56.0-82.2%) in arm B. The hazard ratio was 2.18 (95% CI: 0.95 to 4.98), with the predicted probability of showing the superiority of arm B at the final analysis estimated to be 1.3%. The study was terminated early due to futility. O 6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status was measured in 115 tumors, and it was neither prognostic nor predictive of TMZ response.

CONCLUSIONS

This study failed to demonstrate the benefit of concomitant and maintenance TMZ in newly diagnosed PCNSL.

Anatomical and neurophysiological localization of the leg motor area at the medial central sulcus

OBJECTIVE

The exact location of the leg motor area is still in debate due to the lack of landmarks such as 'precentral knob' in the medial cortex. This study tried to identify the leg motor area based on intraoperative neurophysiological data and neuroimaging techniques.

METHODS

Intraoperative data of somatosensory evoked potential (SEP) elicited by tibial nerve stimulation and motor evoked potential (MEP) of the leg muscles induced by direct cortical stimulation were recorded using subdural electrodes placed in the medial cortex. We displayed the neurophysiological data on the individual MR images and the MNI52.

RESULTS

Definite N40-P40 phase reversal was observed with the shallow grooves in the medial cortex in 5 cases. Leg MEP was successfully obtained in all 12 cases preserving the leg motor function. Superimposed SEP and leg MEP data on the MNI152 indicated the leg motor area was predominantly located in the posterior two-thirds between the vertical lines passing through the anterior commissure and the posterior commissure (VCP).

CONCLUSIONS

Our study revealed the location of the leg motor area and the presence of the 'medial central sulcus' in the medial cortex.

SIGNIFICANCE

The VCP can be useful landmark to identify the sensorimotor border in the medial cortex.

Ventricular opening and cerebrospinal fluid circulation accelerate the biodegradation process of carmustine wafers suggesting their immunomodulation potential in the human brain

PURPOSE

Opening the ventricular system during glioblastoma surgery is often necessary, but the consequent effect on the tumor microenvironment of glioblastoma remains unknown. Implantation of carmustine wafer enables direct drug delivery to the tumor site; however, the exact mechanism of the wafer's biodegradation process is unclear, and the available data is limited to in vivo non-human mammalian studies. We hypothesized that the ventricular opening affects the degradation process of the wafer and the glioblastoma tumor microenvironment.

METHODS

This study included 30 glioblastoma patients. 21 patients underwent carmustine wafer implantation during initial surgery. All patients underwent repeated surgical resection upon recurrence, allowing for pathological comparison of changes associated with wafer implantation. Immunohistochemical analyses were performed using CD68, TMEM119, CD163, IBA1, BIN1, and CD31 antibodies to highlight microglia, macrophages, and tumor vascularity, and the quantitative scoring results were correlated with clinical, molecular, and surgical variables, including the effect of the ventricular opening.

RESULTS

The carmustine wafer implanted group presented significantly less TMEM119-positive microglia within the tumor (P = 0.0002). Simple and multiple regression analyses revealed that the decrease in TMEM119-positive microglia was correlated with longer intervals between surgeries and opened ventricular systems. No correlation was observed between age, methylated O6-methylguanine DNA methyltransferase promoter expression, and the extent of surgical resection.

CONCLUSIONS

Our study findings strongly suggest that biomaterials may possess immunomodulation capacity, which is significantly impacted by the ventricular opening procedure. Furthermore, our data highlights the pathophysiological effects of the ventricular opening within the surrounding human brain, especially after the wafer implantation.

Phase II single-arm, multi-center, physician-initiated clinical trial of convection-enhanced delivery of nimustine hydrochloride (ACNU) against diffuse intrinsic pontine gliomas

2071

Background: Diffuse intrinsic pontine glioma (DIPG) is one of the deadliest central nervous system tumors of childhood, with a 1 year survival of 40%. Intracerebral convection-enhanced delivery (CED) is an approach for administering chemotherapy to patients with brain tumors. We present the results of a multi-institute physician-initiated phase II clinical trial of CED of nimustine hydrochloride (ACNU) against DIPGs. Methods: We did a phase 2, single-arm, multi-center, prospective, physician-initiated clinical trial. Eligible patients were aged 3–21 years and had initially diagnosed DIPG. A Karnofsky performance score of at least 50 at study entry; and had completed standard external beam radiation therapy at least 4 weeks but no more than 5 weeks before enrollment. Accrual of 20 patients were planned. The 1 year survival rate from study entry was set as the primary endpoint, and prespecified threshold of the lower limit level of the 95% confidence interval was set as 30%. CED of 7 mL ACNU at the concentration of 0.75 mg/mL was given intratumorally through the 1-2 cannulas implemented surgically. Use of oral or intravenous temozolomide chemotherapy was allowed simultaneously with CED of ACNU. The analysis of the primary endpoint was done in the per-protocol population (patients who received the full dose of treatment), and all patients who was recruited in this trial were included in the safety analysis. This study is registered with Japan Registry of Clinical Trials (jRCT2021190003). Results: From April, 2018 to March, 2020, 21 children were enrolled in the trial, of whom 20 were evaluable for the primary endpoint. ACNU was not given for one patient because of the adverse event of intracerebral hemorrhage due to catheter insertion surgery. Other than this patient, all 20 patients got 1-2 catheters inserted and received CED of ACNU. For these patients, CED of 7 mL ACNU at the concentration of 0.75 mg/mL was given intratumorally through the 1-2 cannulas implemented surgically. Temozolomide chemotherapy was administered simultaneously in 15 patients. As a result, progression-free survival was 8.0 months and overall survival was 15 months. 1 year survival from recruitment was 55% and was 65% from initiation of standard radiation therapy. Conclusions: As the lower limit level of the 95% confidence interval of the 1 year survival rate from recruitment to the study, which was the primary end-point of the study, exceeded prespecified threshold of 30%, CED of ACNU in the brainstem of children with diffuse intrinsic pontine glioma who have previously received radiation therapy seems to be an effective therapeutic strategy. This therapeutic strategy warrants further development for children with DIPG. Clinical trial information: jRCT2021190003.

Molecular analyses of rosette-forming glioneuronal tumor of the midbrain tegmentum: A report of two cases and a review of the FGFR1 status in unusual tumor locations

Background:

Rosette-forming glioneuronal tumor (RGNT) is a rare tumor that arises primarily in the posterior fossa, with molecular features of FGFR1 mutation. A previous study reported that brainstem RGNT accounts for only 2.7% cases; therefore, midbrain RGNT is infrequent.

Case Description:

The authors encountered two cases of RGNT located in the midbrain tegmentum (Case 1: 23-year-old woman and Case 2: 18-year-old boy), both exhibiting similar cystic components with gadolinium-enhanced cyst walls on preoperative magnetic resonance imaging, surgically resected through the occipital transtentorial approach. Histological findings in both cases comprised two characteristic architectures of neurocytic and glial components, typical of RGNT. Molecular assessment revealed no FGFR1 mutation in the initial specimen, but revealed FGFR1 K656E mutation in the recurrent specimen in Case 1 and showed no FGFR1 mutation but showed TERT C228T mutation in Case 2. Neither case revealed IDH1/2, BRAF, H3F3A K27, H3F3A G34, or HIST1H3B K27 mutations. DNA methylation-based classification (molecularneuropathology.org) categorized both cases as RGNT, whose calibrated scores were 0.99 and 0.47 in Cases 1 and 2, respectively.

Conclusion:

Midbrain tegmentum RGNTs exhibited typical histological features but varied FGFR1 statuses with TERT mutation. RGNT in rare locations may carry different molecular alterations than those in other common locations, such as the posterior fossa.

Ribosomal proteins induce stem cell-like characteristics in glioma cells as an "extra-ribosomal function"

The characteristic features of plasticity and heterogeneity in glioblastoma (GB) cells cause therapeutic difficulties. GB cells are exposed to various stimuli from the tumor microenvironment and acquire the potential to resist chemoradiotherapy. To investigate how GB cells acquire stem cell-like phenotypes, we focused on ribosomal proteins, because ribosome incorporation has been reported to induce stem cell-like phenotypes in somatic cells. Furthermore, dysregulation of ribosome biogenesis has been reported in several types of cancer. We focused on ribosomal protein S6, which promotes sphere-forming ability and stem cell marker expression in GB cells. We expect that investigation of dysregulation of ribosome biogenesis and extra-ribosomal function in GB will provide new insights about the plasticity, heterogeneity, and therapeutic resistance of GB cells, which can potentially lead to revolutionary therapeutic strategies.

Coexistence of anterior cranial fossa dural arteriovenous fistula and arteriovenous malformation with the same drainage system: illustrative case

BACKGROUND

The authors report a rare case of coexistence of dural arteriovenous fistula (DAVF) and arteriovenous malformation (AVM), with a common trunk drainer from both DAVF and AVM in the left anterior cranial fossa (ACF) with simple DAVF in the right ACF.

OBSERVATIONS

A 63-year-old female presented with seizure. Cerebral angiography showed bilateral DAVFs in the ACF and AVM in the left frontal lobe. A dilated frontal vein acted as a simple drainer of the right DAVF. In contrast, a dilated vein with large varix was the common drainer of both the left DAVF and the AVM. During surgery, indocyanine green videoangiography was performed with direct observation. In the left ACF, the drainer occlusion of the DAVF resulted in partial shrinkage of the varix and decreased distal blood flow. Additional main feeder occlusion of the AVM could decrease the blood flow further, but not completely because of the residual pial supplies for the AVM. Finally, the nidus of the AVM with varix was removed by en bloc resection.

LESSONS

Neurosurgeons should be aware of the coexistence of DAVF and AVM with a common trunk drainer. Only simple occlusion of the drainer from DAVF is not sufficient, so removal of the AVM is essential.

A Case of Synchronous Occurrence of Intracranial Germinoma and Systemic Sarcoidosis

Although the synchronous occurrence of testicular seminoma and systemic sarcoidosis has been reported, that of intracranial germinoma and systemic sarcoidosis is unknown. A 26-year-old man presented with symptoms of panhypopituitarism and consciousness disturbance. Imaging demonstrated a large nodule in the upper right lung field and swelling of multiple bilateral pulmonary and mediastinal lymph nodes in addition to the bifocal pineal and suprasellar tumors with obstructive hydrocephalus. The pathological diagnosis of the intracranial bifocal tumors was pure germinoma, whereas that of the mediastinal lymph nodes was epithelioid granuloma. Three courses of chemotherapy using carboplatin and etoposide were administered, followed by whole ventricle irradiation. The intracranial tumors completely disappeared, but the lung nodule and mediastinal lymph nodes progressed. Whole-body fluorine-18-fluorodeoxyglucose positron emission tomography demonstrated accumulation in the mediastinal lymphadenopathy, lung masses, and multiple lymph nodes of the whole body. Transbronchial lung biopsy revealed epithelioid granuloma with multinucleated giant cells. In conjunction with the high blood concentration of angiotensin-converting enzyme and soluble interleukin-2 receptor, these findings established a diagnosis of sarcoidosis. This is the first report of synchronous occurrence of intracranial germinoma and sarcoidosis. Such coexistence is extremely rare, but we should mind that sarcoidosis can occur with intracranial germinoma.

Role of the parietooccipital fissure and its implications in the pathophysiology of posterior medial temporal gliomas

OBJECTIVE

The parietooccipital fissure is an anatomical landmark that divides the temporal, occipital, and parietal lobes. More than 40% of gliomas are located in these three lobes, and the temporal lobe is the most common location. The parietooccipital fissure is located just posterior to the medial temporal lobe, but little is known about the clinical significance of this fissure in gliomas. The authors investigated the anatomical correlations between the parietooccipital fissure and posterior medial temporal gliomas to reveal the radiological features and unique invasion patterns of these gliomas.

METHODS

The authors retrospectively reviewed records of all posterior medial temporal glioma patients treated at their institutions and examined the parietooccipital fissure. To clarify how the surrounding structures were invaded in each case, the authors categorized tumor invasion as being toward the parietal lobe, occipital lobe, isthmus of the cingulate gyrus, insula/basal ganglia, or splenium of the corpus callosum. DSI Studio was used to visualize the fiber tractography running through the posterior medial temporal lobe.

RESULTS

Twenty-four patients with posterior medial temporal gliomas were identified. All patients presented with a parietooccipital fissure as an uninterrupted straight sulcus and as the posterior border of the tumor. Invasion direction was toward the parietal lobe in 13 patients, the occipital lobe in 4 patients, the isthmus of the cingulate gyrus in 19 patients, the insula/basal ganglia in 3 patients, and the splenium of the corpus callosum in 8 patients. Although the isthmus of the cingulate gyrus and the occipital lobe are located just posterior to the posterior medial temporal lobe, there was a significantly greater preponderance of invasion toward the isthmus of the cingulate gyrus than toward the occipital lobe (p = 0.00030, McNemar test). Based on Schramm's classification for the medial temporal tumors, 4 patients had type A and 20 patients had type D tumors. The parietooccipital fissure determined the posterior border of the tumors, resulting in a unique and identical radiological feature. Diffusion spectrum imaging (DSI) tractography indicated that the fibers running through the posterior medial temporal lobe toward the occipital lobe had to detour laterally around the bottom of the parietooccipital fissure.

CONCLUSIONS

Posterior medial temporal gliomas present identical invasion patterns, resulting in unique radiological features that are strongly affected by the parietooccipital fissure. The parietooccipital fissure is a key anatomical landmark for understanding the complex infiltrating architecture of posterior medial temporal gliomas.

PEDT-3

Background: Germ cell tumors (GCTs) containing a teratoma component is a group of diseases consisting of various pathological conditions such as mature teratoma, immature teratoma, teratoma with malignant transformation, and mixed tumor with other GCTs. There is controversy about the efficacy and safety of radiation and chemotherapy for GCTs with teratoma component other than mature teratomas. Methods: Of 212 cases of GCTs treated at Tohoku University Hospital Neurosurgery from January 1990 to March 2021. In this study, 23 histologically verified GCTs containing teratoma components were included. Pathological findings, recurrence, survival, and late complications were examined. Results: The age of onset was 2 months-21 years (median 10.5 years). Histological diagnosis was mature teratoma alone in 5 cases, mixed GCTs with mature teratoma in 11 cases, immature teratoma in 5 cases, and mixed tumor with mature teratoma and germinoma in 2 cases. Patients except mature teratoma were treated by chemotherapy alone or radiochemotherapy. During follow-up for 7–362 months (median 135 months), 3 patients relapsed. One of these patients was diagnosed with mature teratoma at the time of treatment and did not receive post-treatment, but relapsed as germinoma 21 years later. A review of pathological specimens at the time of initial onset revealed immature teratomas in addition to mature teratomas. Recurrent lesions in 3 cases were controlled by additional treatment, and no deaths due to tumor progression were observed. On the other hand, of the 18 patients who underwent radiochemotherapy, 1 developed primary hypothyroidism and 2 developed thyroid cancer and leukemia. Conclusion: GCTs with teratoma component often contain malignant histological types and require caution when making a pathological diagnosis. In these cases, tumor control can be expected by radiation or chemotherapy, but there is a risk of developing endocrine disorders and secondary tumors, and further studies are needed to optimize treatment.

NI-19 A case of Leber’s hereditary optic neuropathy with diffuse white matter changes mimicking gliomatosis cerebri

BACKGROUND: Leber’s hereditary optic neuropathy (LHON) is a mitochondrial disease characterized by bilateral severe subacute central vision loss and a mutation in the mitochondrial DNA (mtDNA). The cranial magnetic resonance imaging (MRI) of LHON patients varies from subtle to multiple white matter changes. However, they rarely present with diffuse infiltrative white matter changes. CASE REPORT: We report a case with diffuse white matter changes mimicking gliomatosis cerebri (GC). The histological findings included only mild glial hyperplasia without immunohistochemical positivity supporting the diagnosis of glial tumors. Analysis of mtDNA obtained from the blood and brain tissue revealed mutation of m.11778G>A in the NADH dehydrogenase 4 gene, which confirmed the case as LHON. Immunohistochemistry of the brain tissue revealed 8-hydroxy-2’-deoxyguanosine positivity, suggesting the presence of oxidative stress. CONCLUSION: LHON is extremely difficult to diagnose unless we suspect or know the disease. The present case brings attention not only to LHON but other mtDNA mutated diseases that need to be considered with diffuse white matter changes or GC.

Association between IDH mutational status and tumor-associated epilepsy or venous thromboembolism in patients with grade II and III astrocytoma

In previous studies, isocitrate dehydrogenase (IDH) mutations were associated with tumor-associated epilepsy (TAE) and venous thromboembolism (VTE). We examined the relationship between IDH mutations in grade II/III astrocytomas and TAE/VTE according to the 2016 World Health Organization classification. The clinical data of patients with newly diagnosed grade II/III gliomas who were treated at Tohoku University Hospital from January 2010 to December 2018 were reviewed. Associations between TAE or VTE and the clinical/biological characteristics, histology, and IDH1/2 mutational status in patients with grade II/III gliomas were evaluated. Of the initial 137 patients (290 hospitalizations), 117 patients (203 hospitalizations) were included in the TAE group and 124 patients (213 hospitalizations) were included in the VTE group. Seventy-eight patients (66.7%) in the TAE group were diagnosed with astrocytoma and 38/78 (48.3%) presented with TAE. According to the multivariable analysis, the IDH mutational status and male sex were associated independently with an increased risk of TAE (p < 0.05). Eighty-five patients (68.5%) in the VTE group were diagnosed with astrocytoma. VTE was observed in 16/161 (9.9%) hospitalizations. According to the multivariable analysis, age, diffuse astrocytoma histology, and resection were associated independently with an increased risk of VTE. The decision tree analysis showed that TAE was more frequent in younger patients while VTE was more frequent in older patients. This study demonstrated that the IDH mutational status was associated with TAE but not with VTE. Therefore, a future large-scale study is needed to provide sufficient evidence. TAE was more common in young patients, while VTE was more common in the elderly.

Leber’s hereditary optic neuropathy with diffuse white matter changes mimicking gliomatosis cerebri: illustrative case

BACKGROUIND

Leber’s hereditary optic neuropathy (LHON) is a mitochondrial disease characterized by bilateral severe subacute central vision loss and a mutation in the mitochondrial DNA (mtDNA). The findings on cranial magnetic resonance imaging of patients with LHON vary from subtle to multiple white matter changes. However, they rarely present with diffuse infiltrative white matter changes.

OBSERVATIONS

The authors reported a case with diffuse white matter changes mimicking gliomatosis cerebri (GC). The histological findings included only mild glial hyperplasia without immunohistochemical positivity, supporting the diagnosis of glial tumors. Analysis of mtDNA obtained from the blood and brain tissue revealed mutation of m.11778G>A in the NADH dehydrogenase 4 gene, which confirmed the case as LHON. Immunohistochemistry of the brain tissue revealed 8-hydroxy-2′-deoxyguanosine positivity, suggesting the presence of oxidative stress.

LESSONS

LHON is extremely difficult to diagnose unless one suspects or knows the disease. The present case brings attention not only to LHON but also to other mtDNA-mutated diseases that need to be considered with diffuse white matter changes or GC.

Necessity for craniospinal irradiation of germinoma with positive cytology without spinal lesion on MR imaging-A controversy

Background

Cerebrospinal fluid (CSF) cytology and spinal MR imaging are routinely performed for staging before treatment of intracranial germinoma. However, the interpretation of the results of CSF cytology poses 2 unresolved clinical questions: (1) Does positive CSF cytology correlate with the presence of spinal lesion before treatment? and (2) Is craniospinal irradiation (CSI) necessary for patients with positive CSF cytology in the absence of spinal lesion?

Methods

Multicenter retrospective analyses were performed based on a questionnaire on clinical features, spinal MR imaging finding, results of CSF cytology, treatments, and outcomes which was sent to 86 neurosurgical and 35 pediatrics departments in Japan. Pretreatment frequencies of spinal lesion on MR imaging were compared between the patients with positive and negative cytology. Progression-free survival (PFS) rates were compared between patients with positive CSF cytology without spinal lesion on MR imaging treated with CSI and with whole brain or whole ventricular irradiation (non-CSI).

Results

A total of 92 germinoma patients from 45 institutes were evaluated by both CSF cytology and spinal MR images, but 26 patients were excluded because of tumor markers, the timing of CSF sampling or incomplete estimation of spinal lesion. Of the remaining 66 germinoma patients, spinal lesions were equally identified in patients with negative CSF cytology and positive cytology (4.9% and 8.0%, respectively). Eleven patients treated with non-CSI had excellent PFS comparable to 11 patients treated with CSI.

Conclusion

CSI is unnecessary for germinoma patients with positive CSF cytology without spinal lesions on MR imaging.

Postcentral gyrus resection of opercular gliomas is a risk factor for motor deficits caused by damaging the radiologically invisible arteries supplying the descending motor pathway

BACKGROUND

Postoperative motor deficits are among the worst morbidities of glioma surgery. We aim to investigate factors associated with postoperative motor deficits in patients with frontoparietal opercular gliomas.

METHODS

Thirty-four patients with frontoparietal opercular gliomas were retrospectively investigated. We examined the postoperative ischemic changes and locations obtained from MRI.

RESULTS

Twenty-one patients (62%) presented postoperative ischemic changes. Postoperative MRI was featured with ischemic changes, all located at the subcortical area of the resection cavity. Six patients had postoperative motor deficits, whereas 28 patients did not. Compared to those without motor deficits, those with motor deficits were associated with old age, pre- and postcentral gyri resection, and postcentral gyrus resection (P = 0.023, 0,024, and 0.0060, respectively). A merged image of the resected cavity and T1-weighted brain atlas of the Montreal Neurological Institute showed that a critical area for postoperative motor deficits is the origin of the long insular arteries (LIAs) and the postcentral gyrus. Detail anatomical architecture created by the Human Connectome Project database and T2-weighted images showed that the subcortical area of the operculum of the postcentral gyrus is where the medullary arteries supply, and the motor pathways originated from the precentral gyrus run.

CONCLUSIONS

We verified that the origin of the LIAs could damage the descending motor pathways during the resection of frontoparietal opercular gliomas. Also, we identified that motor pathways run the subcortical area of the operculum of the postcentral gyrus, indicating that the postcentral gyrus is an unrecognized area of damaging the descending motor pathways.

H3K27M and TERT promoter mutations are poor prognostic factors in surgical cases of adult thalamic high-grade glioma

Background

Thalamic high-grade gliomas (HGGs) are rare tumors with a dismal prognosis. H3K27M and telomerase reverse transcriptase promoter (TERTp) mutations reportedly contribute to poor prognoses in HGG cases. We investigated the outcomes of surgically treated adult thalamic HGGs to evaluate the prognostic significance of H3K27M and TERTp mutations.

Methods

We retrospectively analyzed 25 adult patients with thalamic HGG who underwent maximum surgical resection from January 1997 to March 2020. The histological and molecular characteristics, progression-free survival (PFS), and overall survival (OS) of the patients were compared. For molecular characteristics, target sequencing was used to determine the H3F3A, HIST1H3B, and TERTp mutations.

Results

H3K27M mutations were detected in 12/25 (48.0%) patients. TERTp mutations were not detected in H3K27M-mutant gliomas but were detected in 8/13 (61.5%) of H3 wild-type gliomas. Although it was not significant, H3K27M-mutant gliomas tended to have a shorter PFS (6.7 vs 13.1 months; P = .2928) and OS (22.8 vs 24.4 months; P = .2875) than H3 wild-type gliomas. Moreover, the prognosis of TERTp-mutant gliomas was as poor as that of H3K27M-mutant gliomas. Contrary, 5 gliomas harboring both H3 and TERTp wild-type showed a better median PFS (59.2 vs 6.4 months; P = .0456) and OS (71.8 vs 24.4 months; P = .1168) than those harboring H3K27M or TERTp mutations.

Conclusions

TERTp-mutant gliomas included in the H3 wild-type glioma group limited patient survival as they exhibited an aggressive course similar to H3K27M-mutant gliomas. Comprehensive molecular work-up for the H3 wild-type cases may further confirm this finding.

Long-term follow-up after BCNU wafer implantation in patients with newly diagnosed glioblastoma

1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU, or Carmustine) wafers are intraoperatively implantable wafers used to achieve local tumor control. There is scarce data about the behavior of wafers in the long-term follow-up of implanted cases. We reviewed the data of 64 patients with newly diagnosed glioblastoma treated by surgery, BCNU wafers, radiation therapy, and temozolomide administration. This cohort included 55 patients who presented first recurrence, and 49 of them showed tumor progression to death. The MR imaging of each patient at the terminal stage and an autopsy case were used to elucidate the tumor progression pattern after the wafer implantation. We subdivided the first recurrence pattern into local, distant, and multifocal based on MR imaging or into infield, outfield, and marginal based on the radiation field. The first recurrence pattern was 33 patients (60%) with local, 13 (24%) with distant, and nine (16%) with multifocal recurrence, or 38 patients (69%) with infield, 13 (24%) with outfield, and four (7%) with marginal. The median and mean time intervals between MR imaging at the terminal stage and death were 2.0 and 2.3 months, respectively. Of note, 13 patients with first distant recurrence had no obvious radiological local tumor progression even at the terminal stage. Long-term follow-up after BCNU wafer implantation revealed that patients with first distant recurrence had long-lasting local tumor control until the terminal stage.

SURG-16. SURGICAL TECHNIQUES TO AVOID COMPLICATIONS DURING REPEAT RESECTIONS FOR PEDIATRIC BRAIN TUMORS

Complications due to repeat resection for recurrent pediatric brain tumors remain unclear. The present study focused on surgical techniques to avoid surgical morbidities during repeat resections for pediatric brain tumors. This study included 57 consecutive repeat resections for 28 pediatric patients under the age of 15 with recurrent brain tumors. Resections were performed 2–14 times for each patient by the senior author (TK). Reviewed factors were wound-related complications, bleeding/ischemic complications, and Eastern Cooperative Oncology Group performance status (PS) before and after surgery. No patients presented any complications to decrease PS, postoperatively. No wound-related complications were worthy of special mention. Surgical techniques to prevent wound-related complications are as follows: 1) shaving the hair around the previous skin incision just before the surgery; 2) washing and disinfecting around the skin incision using chlorhexidine soap and an alcohol swab, followed by Povidone-Iodine solution; 3) after craniotomy, removing all granulation tissues, residual titanium plates, and screws; 4) brushing all surgical fields and a bone flap before opening the dura mater using Povidone-Iodine solution followed by normal saline; 5) maintaining a bone flap in normal saline with antibiotics; 6) changing all the surgical instrument and gloves; 8) closing the dura mater completely to prevent CSF leakage, and 8) using postoperative antibiotics for six days. Meticulous dissecting postsurgical adhesion of brain and dura mater, arteries and nerves; usage of neuronavigation system and neuromonitoring to understand the anatomy radiologically and functionally; applying papaverine hydrochloride for spastic arteries, are important to avoid complications during the intracranial procedure.

Unilateral chronic subdural hematoma due to spontaneous intracranial hypotension: a report of four cases

Background: Chronic subdural hematoma (CSDH) is a common neurosurgical disease. A subset of patients with CSDH may exhibit underlying spontaneous intracranial hypotension (SIH). Bilateral CSDH has a causal relationship with SIH, but there is no known causal relationship between unilateral CSDH and SIH.Case description: We encountered four cases of unilateral CSDH due to SIH. The patients' age ranged between 44 and 64 years; there were three males and one female. All patients presented with headache as their initial symptom, and then became comatose. Computed tomography demonstrated unilateral CSDH and transtentorial herniation in all patients. Treatments were emergency epidural blood patch (EBP) and evacuation of CSDH. The site of cerebrospinal fluid leak could not be identified in three patients; therefore, EBP was performed at upper and lower spine. All patients recovered from SIH; however, one patient experienced poor outcome due to Duret hemorrhage and ischemic complications of transtentorial herniation. Cranial asymmetry was present in all four patients, and unilateral CSDH was located on the side of the most curved cranial convexity.Conclusions: Unilateral CSDH, asymmetric cranial morphology, and transtentorial herniation in relatively young patients may indicate underlying SIH.

PEDT-02 Clinical usage of NCC Oncopanel/FoundationOne CDx for pediatric/AYA patients with recurrent malignant brain tumors

Backgrounds: Analyses of somatic mutations in malignant brain tumors have been used to make effective treatment strategies. NCC Oncopanel and FoundationOne CDx are custom targeted next-generation sequencing (NGS) panels. The cost for this analysis is 560,000 yen covered by National Health Insurance in Japan since June 2019. These methods can be applied for the solid cancers with no established therapies and relapsed after the standard therapies. Following these inclusion criteria, most malignant brain tumors, especially recurrent malignant brain tumors in pediatric/AYA generations, can be included. Object: To report the results of our initial experiences. Methods: In the last one year, we utilized these NGS panels for five patients with recurrent malignant brain tumors in this generations: 2 epithelioid glioblastomas; 1 anaplastic meningioma; 1 diffuse astrocytoma (gliomatosis cerebri); 1 atypical choroid plexus papilloma. Results: Final recommended treatments are as follows: BRAF/MEK inhibitors, bevacizumab, or anti-PD-1 antibody for one epithelioid glioblastoma; MEK inhibitor for another epithelioid glioblastoma previously treated by BRAF inhibitor and bevacizumab; ERK1/2 inhibitors for anaplastic meningioma. The diffuse astrocytoma had IDHR132H mutation. There was no clinical trial using IDH inhibitor for recurrent diffuse astrocytoma; thus, the final recommendation for this case was rechallenge of temozolomide. To date, only one NGS for a choroid plexus papilloma has been reported (Arch Pathol Lab Med, 2017). Our case had multiple actionable gene alterations, including TERT mutation and amplification of various genes. Unfortunately, there was no druggable gene alteration among them. Conclusions: Insurance-covered cancer gene panel tests could represent effective treatment options for some malignant brain tumors in pediatric/AYA generations. If the relapse is local and can be treated by repeat resections, we think the surgery is the first-line choice. But, in another situation, information from NGS panels should be obtained positively. Efforts to increase the utility of off-label use of drugs are encouraged.

ACT-03 Clinical outcome and radiological findings of patients with recurrent glioblastomas treated by bevacizumab

Object: Seven years have passed since the approval of bevacizumab (BEV) in Japan. We retrospectively reviewed the clinical outcome and radiological findings of patients with recurrent glioblastomas (GB) treated by BEV. Method: We reviewed 116 patients, including 27 cases of newly diagnosed GB and 89 cases of recurrent GB, treated by BEV during the study period between 2013 June and 2019 September. Cumulatively, 116 patients received 1672 cycles of BEV. Among those, we focused on 74 patients with newly diagnosed GB treated by BEV at recurrence to examine clinical characteristics, outcome, and radiological findings of T2-circumscribed or double-positive proposed by Nowosieski et al. or Bahr et al., respectively. Result: The study cohort comprised median age of 66.8 years (range 10 to 81), median KPS of 60% (range, 20 to 100), median cycles of administration 11(1 to 59), median period of treatment 172 days (0 to 1413), median post-BEV survivals 266 days, and overall survival 693 days. Patients without progressive disease at 6 months post-BEV MRI (n = 23) presented favorable post-BEV survival of 713 days than those with progressive disease (n = 8) (p=0.0003). The radiological findings varied by patients, tumor lesions, and sequential imaging; thus, it was difficult to correlate with survival. Our data implied that the T2-circumscribed lesion was accompanied by no enhancement at T1 but hyperperfused at arterial spin labeling imaging, indicating that blood-brain barriers were intact and vascularization is activated. Conclusion: Although our cohort included patients with relatively high age, some had prolonged post-BEV survival. T2-circumscribed or double-positive was not useful to predict the survival; however, MRI at 6 months post-BEV can be an indicator for two years of post-BEV survival.

CBMS-09 Intercellular communication at glioblastoma stem cell niches

Glioblastoma multiforme (GBM) contains heterogenous population of cells including a small population of GBM stem cells (GSCs), which potentially cause therapeutic resistance and tumor recurrence. GSCs harbored in special microenvironments, such as perinecrotic niche, perivascular niche, border niche. However, the mechanisms underlying the pathogenesis and maintenance of GSCs remain largely unknown. Stemness and chemo-radioresistance was promoted by not only additional mutation, but also microenvironment of GBM cells. Previously, we had reported that growth factors and cytokines secreted by oligodendrocyte lineage cells and macrophages/microglia induce stemness and chemo-radioresistance into GBM cells. Recently, Ito et al. reported that incorporation of ribosomes and ribosomal proteins into somatic cells promoted lineage trans-differentiation toward multipotency. Ribosomal proteins exist intra- and extracellularly. There is a possibility that ribosomal proteins promote stemness into cancer cells, we focused on 40S ribosomal protein S6 (RPS6), which is related to cell proliferation in lung and pancreatic cancer, but not reported in GBM. RPS6 was significantly upregulated in high-grade glioma. SiRNA-mediated RPS6 knock-down significantly suppressed the characteristics of GSCs, including their tumorsphere potential and stemness marker expression, such as Nestin and Sox2. RPS6 overexpression enhanced the tumorsphere potential of GSCs. Moreover, RPS6 expression was significantly correlated with SOX2 expression in different glioma grades. Immunohistochemistry data indicated that RPS6 was predominant detected at GSC niches, concurrently with the data from IVY GAP databases. Furthermore, RPS6 and other ribosomal proteins were upregulated in GSC-predominant areas in this database. The present results indicate that, in GSC niches, ribosomal proteins play crucial roles in the development and maintenance of GSCs and are clinically associated with chemo-radioresistance and GBM recurrence. These results suggested that intercellular communications through growth factors, cytokines, and ribosomes are regarded as new treatment targets of GBM.

ML-01 Pathological characteristics of primary central nervous system lymphoma with atypical radiological finding

Background: If the brain tumor is suspected to be a primary central nervous system lymphoma (PCNSL) on radiological findings, it is general to perform biopsy to obtain the pathological diagnosis. Glioblastomas (GBs) must be distinguished from PCNSLs. In addition to commonly used contrast-enhanced T1-weighted imaging, diffusion-weighted image (DWI), and apparent diffusion coefficient (ADC) value, the following characteristics of PCNSLs were reported to be essential for this purpose: 1) no increase in blood flow on perfusion images obtained by the arterial spin labeling (ASL) method; 2) less microbleeding on T2*-weighted images (T2*). However, we experienced some exceptional cases. Purpose: To clarify the histopathological features of PCNSLs those had atypical radiological findings. Method: 62 consecutive PCNSL cases (40 males, 22 females, mean age 65.4 years, range 35–84) treated in our department from April 2013 to March 2020 were retrospectively analyzed. We compared the following features between 47 biopsy cases showing typical image findings as PCNSLs (Group A) and 15 surgically resected cases with atypical findings (Group B), 1) number of blood vessels per hyper 10 fields, 2) occupying area of blood vessels per unit area, 3) immunoreactivity of vascular endothelial growth factor (VEGF), and 4) germinal center B-cell (GCB) subtype. Results: In Group A, the number of blood vessels in the tumor was 39.3 on average, and the area occupied by blood vessels was 3.8%. In Group B, the former was 133.2, and the latter was 9.9%. There was no significant difference in VEGF expression and GCB subtype. Conclusion: In PCNSLs showing with high blood flow and microbleeds, the blood vessels were rich and partial bleeding was confirmed histologically. We should analyze much more cases to set the threshold both of the ADC value and the absolute value of blood flow calculated by the ASL method to distinguish between PCNSLs and GBs.

TERT promoter mutation associated with multifocal phenotype and poor prognosis in patients with IDH wild-type glioblastoma

Background

Although mutations in the promoter region of the telomerase reverse transcriptase (TERTp) gene are the most common alterations in glioblastoma (GBM), their clinical significance remains unclear. Therefore, we investigated the impact of TERTp status on patient outcome and clinicopathological features in patients with GBM over a long period of follow-up.

Methods

We retrospectively analyzed 153 cases of GBM. Six patients with isocitrate dehydrogenase 1 (IDH1) or H3F3A gene mutations were excluded from this study. Among the 147 cases of IDH wild-type GBM, 92 (62.6%) had the TERTp mutation. Clinical, immunohistochemical, and genetic factors (BRAF, TP53 gene mutation, CD133, ATRX expression, O⁶-methylguanine-DNA methyltransferase [MGMT] promoter methylation) and copy number alterations (CNAs) were investigated.

Results

GBM patients with the TERTp mutation were older at first diagnosis versus those with TERTp wild type (66.0 vs. 60.0 years, respectively, P = .034), and had shorter progression-free survival (7 vs. 10 months, respectively, P = .015) and overall survival (16 vs. 24 months, respectively, P = .017). Notably, magnetic resonance imaging performed showed that TERTp-mutant GBM was strongly associated with multifocal/distant lesions (P = .004). According to the CNA analysis, TERTp mutations were positively correlated with EGFR amp/gain, CDKN2A deletion, and PTEN deletion; however, these mutations were negatively correlated with PDGFR amp/gain, CDK4 gain, and TP53 deletion.

Conclusions

TERTp mutations were strongly correlated with multifocal/distant lesions and poor prognosis in patients with IDH wild-type GBM. Less aggressive GBM with TERTp wild type may be a distinct clinical and molecular subtype of IDH wild-type GBM.

[Surgical Removal of a Superior Medial Midbrain Cavernous Angioma through the Anterior Interhemispheric Transcallosal Transforaminal Approach:A Case Report]

A 33-year-old male presented with sudden onset of dysarthria. MRI showed a single round lesion containing hematomas in varying stages combined with venous malformation in the superior midline portion of the midbrain, indicating a midbrain cavernous angioma. Serial follow-up MRI revealed enlargement of the angioma concomitant with worsening of the dysarthria, ataxia, and intention tremor. Preoperative MRI suggested that the angioma consisted of a cystic hemorrhagic lesion with an 18-mm diameter without hydrocephalus. Since the angioma was located just beneath the floor of the midline portion of the third ventricle, we chose an anterior interhemispheric transcallosal transforaminal approach. After callosotomy, the foramen of Monro was widened by dissecting the choroidal fissure, enabling entry into the third ventricle. The lower part of the massa intermedia was cut;the median floor of the third ventricle was dissected and the angioma was removed. After the surgery, only a transient complication of seesaw nystagmus was observed, caused by damage to the interstitial nucleus of Cajal. As the anterior interhemispheric transcallosal transforaminal approach does not damage both forces, this technique may be a safe and useful approach for superior medial midbrain lesions, located just beneath the floor of the third ventricle.

Randomized phase III study of high-dose methotrexate and whole brain radiotherapy with or without concomitant and adjuvant temozolomide in patients with newly diagnosed primary central nervous system lymphoma: JCOG1114C

2500

Background: Temozolomide (TMZ) is an oral alkylating agent that penetrates the blood-brain barrier with moderate toxicity, and has shown anti-tumor activity in primary central nervous system lymphoma (PCNSL) in single arm studies. Our goal was to determine whether the addition of concomitant and adjuvant TMZ chemotherapy to standard treatment of high-dose methotrexate (HD-MTX) and whole brain radiotherapy (WBRT) for PCNSL improves survival in a randomized controlled trial. Methods: We did an open-label, randomized phase III trial at 30 hospitals in Japan enrolling immunocompetent patients (pts) aged 20-70 years with histologically confirmed newly diagnosed PCNSL. Pts enrolled at step 1 registration received HD-MTX (MTX; 3.5 g/m2 at day 1, 15, 29). Pts who received at least 1 cycle of HD-MTX were randomly assigned (1:1) at step 2 registration to receive WBRT (30 Gy) ± 10 Gy boost (control arm: A) or WBRT ± boost with concomitant TMZ (75 mg/m2 daily) and adjuvant TMZ (150-200 mg/m2 daily for 5 days every 28 days) for two years after initiation of HD-MTX or until tumor progression (experimental arm: B). Randomization was adjusted by institution, PS (0-1 / 2-3), age (≤60/≥61 years), presence or absence of intraparenchymal tumor after HD-MTX. The primary endpoint was overall survival (OS). The planned sample size was 130 pts in total, to provide an 80% power to detect a 0.52 hazard ratio (65% vs 80% in 2y-OS) for arm B to A and a one-sided alpha of 5%. Results: Between September 29, 2014 and October 15, 2018, 134 pts were enrolled, of whom 122 were randomly assigned and analyzed; 62 to arm A and 60 to arm B. At the planned interim analysis, the 2-y OS was 86.8% (95% CI: 72.5-94.0) in arm A and 71.4% (56.0-82.2) in arm B. The hazard ratio was 2.18 (95% CI: 0.95 to 4.98) with predictive probability for showing the superiority of arm B at the final analysis was calculated to be 1.3%. The study was terminated due to futility. The 2-y progression-free survival was 60.6% (43.6-73.8) in arm A and 49.9% (34.4-63.5) in arm B with a hazard ratio of 1.54 (0.88 to 2.70). The most common grade 3 and 4 toxicities were lymphopenia, observed in 7 (11.5%) pts during WBRT in arm A, 18 (30%) pts during WBRT + concomitant TMZ and 18 (37.5%) pts during adjuvant TMZ in arm B. Conclusions: This study failed to demonstrate the benefit of the addition of TMZ to WBRT and adjuvant TMZ in newly diagnosed PCNSL. Possible biomarkers including methylation status of the MGMT promoter in the tumors will be analyzed. Clinical trial information: jRCTs031180207 .

[A Case of Familial Schwannomatosis Occurring as Intraorbital Schwannoma]

A 67-year-old male presenting with left exophthalmos and progressive visual disturbance was referred to our department. Tumors at the supraclavicular fossa and dorsal femoral region were resected at ages 27 and 45 years. His father and son had both been diagnosed with spinal tumors, and his son's tumor was pathologically diagnosed as a schwannoma. Brain MRI of his son demonstrated no intracranial tumor. Brain MRI of the patient revealed a multilobular tumor of 2 cm diameter compressing the optic nerve medially within the left muscle cone, and no other intracranial tumors. However, large masses lateral to the pharynx and intercostal nerve, as well as multiple spinal tumors were detected. Transcranial total resection of the intraorbital tumor was performed. The pathological diagnosis was consistent with a schwannoma. These clinical characteristics fulfilled the diagnostic criteria of familial schwannomatosis. The postoperative course was uneventful. His visual dysfunction and eye movement disorder resolved completely. The intraorbital tumor was believed to originate from the lacrimal nerve. Sequencing of all exons for <i>SMARCB1</i> and <i>LZTR1</i> using DNA extracted from the tumor did not reveal any mutations. This case is the third report on familial schwannomatosis in Japan.

MPC-03 IMMUNOHISTOCHEMICAL ANALYSIS OF TUMOR ASSOCIATED MACROPHAGE INDUCED AFTER BIODEGRADABLE CARMUSTINE WAFER IMPLANTATION IN HUMAN GLIOBLASTOMA

The carmustine (BCNU) wafer, a biodegradable polymer, currently is the only drug that is able to be placed at the surgical site to treat malignant tumors. Biomaterials to treat cancers hold therapeutic potential; however, how they behave inside the tumor microenvironment requires further study. We previously investigated the tumor microenvironment after BCNU wafer implantation, and found that CD68-positive macrophage was significantly introduced around the wafer (Shibahara et al. J Neurooncol 2018). Recent studies demonstrated the importance of tumor-associated macrophage (TAM). However, we could not clarify whether the increased macrophage around the wafer was pro-tumor or anti-tumor phenotype. In the present study, we immunohistochemically examined expressions of CD68, IBA1, CD163, TMEM119, BIN1, CD31, and VEGF to investigate TAM after the wafer implantation. Quantitative evaluation revealed that CD68-positive cells were significantly increased (P = 0.0009), whereas TMEM119-positive cells were significantly decreased (P = 0.0081) after wafer implantation compared to tissue from cases without wafer implantation. CD163, a known marker of poor prognosis in glioblastoma, did not differ with and without wafer implantation. Among factor analyzed, BCNU wafer did not induce protumor TAM, but reduced microglial marker, TMEM119. In addition to the aspect of chemotherapy, BCNU wafer may have potential to modify the tumor microenvironment such as TAM.

RARE-07. HOW TO TREAT THE INCIDENTAL THALAMIC PRESUMED LOW-GRADE GLIOMAS

Medical intervention for patients with incidentally found presumed low grade gliomas (iLGGs) is controversial. We experienced 5 consecutive thalamic iLGGs, and discuss the follow-up methods and the timing of the intervention. Age at the initial MRI was 19, 57, 58, 70, 70, respectively. Only the bilateral thalamic iLGG of 19-year-old male was radically resected soon after the initial MRI, because of the large tumor size. The histological diagnosis was a diffuse astrocytoma, IDH-wildtype, without H3K27M mutation. This patient was treated by chemoradiation, still alive for 24 months with KPS of 90%. The other four cases were strictly followed by MRI. One case of 70-year-old female is followed for 38 months without increasing the tumor volume. The other 3 cases had been followed by MRI for 15, 91, 154 months, respectively. Stereotactic biopsy or ventriculo-peritoneal shunting (VPS) was performed after that because of the tumor progression. The histological diagnosis of 57-year-old male followed for 15 months was a diffuse astrocytoma, IDH-wildtype. This patient selected further follow-up, although volume of the tumor increased exponentially. Radical resection was performed 11 months after the stereotactic biopsy, disclosed malignant transformation. This patient was treated by chemoradiation, finally died of tumor dissemination 15 months after the radical resection. Long-term followed patients, such as 91 and 154 months, showed slow linear tumor volume increasing. The latter patient with bilateral iLGG was treated by VPS followed by radiation therapy. This patient could keep KPS of 100% for 13 years after the initial MRI and live for 20 years. Our case series suggests that conservative management and close follow-up of thalamic iLGGs is a safe and effective strategy. However, volumetric analysis must be performed for every follow-up MRI. Once the steep volume increasing is detected, surgical intervention and/or chemoradiation should be considered without delay.

PATH-14. IMMUNOHISTOCHEMICAL ANALYSIS OF TUMOR ASSOCIATED MACROPHAGE INDUCED AFTER CARMUSTINE WAFER IMPLANTATION IN HUMAN GLIOBLASTOMA

The carmustine (BCNU) wafer, a biodegradable polymer, currently is the only drug that is able to be placed at the surgical site to treat malignant tumors. Biomaterials to treat cancers hold therapeutic potential; however, how they behave inside the tumor microenvironment requires further study. We previously investigated the tumor microenvironment after BCNU wafer implantation, and found that CD68-positive macrophage was significantly introduced around the wafer (Shibahara et al. J Neurooncol 2018). Recent studies demonstrated the importance of tumor-associated macrophage (TAM). However, we could not clarify whether the increased macrophage around the wafer was pro-tumor or anti-tumor phenotype. In the present study, we immunohistochemically examined expressions of CD68, IBA1, CD163, TMEM119, BIN1, CD31, and VEGF to investigate TAM after the wafer implantation. Quantitative evaluation revealed that CD68+ cells were significantly increased (P = 0.0009), whereas TMEM119+ cells were significantly decreased (P = 0.0081) after wafer implantation compared to tissue from cases without wafer implantation. CD163, a known marker of poor prognosis in glioblastoma, did not differ with and without wafer implantation. Among factor analyzed, BCNU wafer did not induce protumor TAM, but reduced microglial marker, TMEM 119. In addition to the aspect of chemotherapy, BCNU wafer may have potential to modify the tumor microenvironment such as TAM.

Recurrent noncoding U1 snRNA mutations drive cryptic splicing in SHH medulloblastoma

Recurrent somatic single nucleotide variants (SNVs) in cancer are largely confined to protein coding genes, and are rare in most pediatric cancers^1–3. We report highly recurrent hotspot mutations of U1 spliceosomal small nuclear RNAs (snRNAs) in ~50% of Sonic Hedgehog medulloblastomas (Shh-MB), which were not present across other medulloblastoma subgroups. This U1-snRNA hotspot mutation (r.3a>g), was identified in <0.1% of 2,442 cancers across 36 other tumor types. Largely absent from infant Shh-MB, the mutation occurs in 97% of adults (Shhδ), and 25% of adolescents (Shhα). The U1-snRNA mutation occurs in the 5′ splice site binding region, and snRNA mutant tumors have significantly disrupted RNA splicing with an excess of 5′ cryptic splicing events. Mutant U1-snRNA mediated alternative splicing inactivates tumor suppressor genes (PTCH1), and activates oncogenes (GLI2, CCND2), represents a novel target for therapy, and constitutes a highly recurrent and tissue-specific mutation of a non-protein coding gene in cancer.

New Radiologic Findings of Hypertrophic Olivary Degeneration in 2 Patients with Brainstem Lymphoma

BACKGROUND

Hypertrophic olivary degeneration (HOD) is a rare neurological condition of trans-synaptic degeneration caused by disruption of the dentatorubro-olivary pathway. We present new radiologic findings of HOD in 2 cases of brainstem lymphoma.

CASE DESCRIPTION

A 35-year-old woman (Case 1) and a 69-year-old man (Case 2) presented with remarkably similar clinical courses. The primary lesion was located at the dorsal pons extending to the midbrain. Pathologic diagnosis of diffuse large B-cell lymphoma was obtained after surgical resection. Complete remission of the primary lesion was achieved by treatment with 3 courses of high-dose methotrexate and radiotherapy. Arterial spin-labeling and T₂-weighted imagings showed high signal intensity in the inferior olive (IO) at some time after the operation. Slight contrast enhancement in the IO was also found in Case 1. These radiologic findings nearly misled us into a diagnosis of recurrence of lymphoma. Signal intensity in the IO on arterial spin-labeling imaging changed with time. Normalized regional cerebral blood flow (rCBF) in the IO was defined as a percentage of rCBF to the global cerebral blood flow calculated using automated software. Chronologic change in normalized rCBF in the IO revealed a large peak in Case 1, but only a mild increase in Case 2. Neurological findings demonstrated severe oculopalatal tremor in Case 1 and mild palatal tremor in Case 2.

CONCLUSIONS

Hyperperfusion and contrast enhancement in the IO were found in 2 patients with HOD. These findings may be confused with recurrence of malignant tumor.

Incidence of initial spinal metastasis in glioblastoma patients and the importance of spinal screening using MRI

PURPOSE

Intracranial glioblastomas with simultaneous spinal lesions prior to chemoradiation therapy or craniotomy, defined as initial spinal metastasis, are not well understood. Herein, we investigated intracranial glioblastoma and demonstrated the importance of spinal screening using gadolinium enhanced spinal magnetic resonance imaging (Gd-MRI).

METHODS

Consecutive adult patients with intracranial glioblastoma were treated between 2010 and 2014 and received spinal screening using Gd-MRI. Spinal screening was performed regardless of spine-related symptoms, and patients presenting with and without initial spinal metastasis (spinal and non-spinal groups, respectively) were compared based on patient demographics, tumor characteristics, radiological and molecular features, and overall survival (OS).

RESULTS

During the study period, 116 glioblastoma cases were treated and 87 of these (76%) underwent spinal screening. Among these patients, 11 (13%) were included in the spinal group, and 76 (87%) were included in the non-spinal group. All patients of the spinal group were free of symptoms related to spinal lesions. Compared with the non-spinal group, intracranial lesions of the spinal group presented higher incidences of intracranial dissemination and were located at subventricular zones (P = 0.0012 and 0.020, respectively). MIB-1 labeling index, molecular alterations such as IDH1 mutation, TERT promoter mutation, and immunoreactivity of ATRX and MGMT did not differ between two groups. OS was significantly shorter in the spinal group than in the non-spinal group (P = 0.0054).

CONCLUSIONS

This study revealed a relatively high incidence of spinal metastasis. A subset of glioblastoma patients benefited from spinal screening, through which early detection of asymptomatic spinal metastasis was achieved.

Safe Stereotactic Biopsy for Basal Ganglia Lesions: Avoiding Injury to the Basal Perforating Arteries

BACKGROUND

One of the most serious complications of stereotactic biopsy is postoperative symptomatic hemorrhage due to injury to the basal perforating arteries such as the lenticulostriate arteries neighboring the basal ganglia lesions.

OBJECTIVES

A new target-planning method was proposed to reduce hemorrhagic complications by avoiding injury to the perforating arteries.

METHODS

Three-dimensional 3-T time-of-flight (3D 3-T TOF) imaging was applied to delineate the basal perforating arteries such as the lenticulostriate arteries. The incidence of postoperative hemorrhage in basal ganglia cases was compared between a new method using 3D 3-T TOF and a conventional target-planning method based on contrast-enhanced T1-weighted magnetic resonance images obtained by 1.5-T scanning.

RESULTS

3D 3-T TOF imaging could delineate the basal perforating arteries sufficiently in target planning. No postoperative hemorrhage occurred with the new method (n = 10), while 6 postoperative hemorrhages occurred with the conventional method (n = 14). The new method significantly reduced the occurrence of postoperative hemorrhages (p = 0.017).

CONCLUSIONS

3D 3-T TOF MR imaging with contrast medium administration provides useful information about the perforating arteries and allows safe stereotactic biopsy of basal ganglia lesions.