Preventing Post-incisional Dural Shrink in Craniotomy: Introducing the "Roll-up Technique".

Dural dryness makes suturing difficult during dural closure after craniotomy. In this case, dural plasty is often performed using a membrane taken from the surrounding tissue (e.g., fascia or periosteum) or an artificial replacement membrane. Herein, we introduce our novel "roll-up technique" to reduce the utilization of substitute membranes and explore its effectiveness in dural closure. We retrospectively examined the medical records of 50 patients who underwent craniotomy for the first time for supratentorial intracranial lesions between 2015 and 2022. Furthermore, we divided them into two groups: (1) the conventional technique group, which consisted of patients in whom the dura mater was flipped after incision and protected with a moistened gauze (n = 23), and (2) the roll-up technique group, which consisted of patients in whom the dura mater was incised in a U shape, rolled up, and protected with a moist gauze (n = 27). After surgery, we compared the success rates of primary closure, operating time, craniotomy area, and percentage of complications (e.g., cerebrospinal fluid [CSF] leakage or infection) between the groups. Dural closure without dural substitutes using the roll-up technique had a higher success rate than that using the conventional technique (26/27 [96.3%] cases vs. 14/23 [60.9%] cases; P = 0.003). Postoperative CSF leakage or infection did not occur, and no statistically significant difference was observed in the operating time between the groups (P = 0.247). The roll-up technique for dural closure may effectively prevent post-incisional dural shrink after craniotomy.

Residual diffusion-weighted imaging hyperintense signal in primary central nervous system lymphoma can predict early recurrence.

BACKGROUND: The treatment response of primary central nervous system lymphomas (PCNSLs) is mainly evaluated using postcontrast T1-weighted imaging (T1WI). Because poorly enhanced lesions may contain residual tumors, the combination of evaluation methods will potentially improve the accuracy of determining treatment effectiveness. In this study, we evaluated the usefulness of diffusion-weighted imaging (DWI) in predicting recurrence among patients with PCNSL who achieved complete response (CR)/unconfirmed CR (CRu). METHODS: Fifty-four patients newly diagnosed with PCNSL who were treated at our institution and achieved CR/CRu at the end of treatment were included in this study. The patients were divided into two groups according to the presence or absence of residual DWI hyperintense signal at the tumor site at the end of treatment. Kaplan-Meier analysis was performed to analyze the median overall survival (OS) and progression-free survival (PFS). RESULTS: The mean age of the 54 patients was 66.4 ± 13.3 years. The induction therapies were HD-MTX in 20 patients, R-MPV in 29 patients, and other chemotherapies in five patients. Radiotherapy was performed in 35 patients, high-dose cytarabine therapy in 14 patients, and autologous hematopoietic stem cell transplantation in one patient, and of the 54 patients, 10 had no consolidation therapy. The residual DWI hyperintense signal sign was observed in 18 patients. The R-MPV regimen was statistically associated with a lower rate of residual DWI hyperintense signal (p = 0.0453). The median PFS was statistically shorter in the residual DWI hyperintense signal group than in the non-residual DWI hyperintense signal group (14.0 months vs. 85.1 months) (p < 0.0001, log-rank test). CONCLUSION: A residual DWI hyperintense signal at the end of treatment was statistically associated with shorter PFS. Among patients who achieved CR/CRu evaluated based on postcontrast T1WI, DWI could be a valuable additional sequence to predict the early recurrence of PCNSL.

Characteristics and therapeutic strategies of brain and cranial radiation-induced sarcoma: analysis of 165 cases from our case experience and comprehensive review.

BACKGROUND: Radiation-induced sarcoma (RIS) is among the neoplasms potentially caused by radiation therapy (RT) for brain tumors. However, the clinical characteristics of and ideal treatment for RIS are unclear. We analysed our case experience and conducted a comprehensive literature review to reveal the characteristics of brain and cranial RIS. METHODS: We analysed 165 cases of RIS from the literature together with the RIS case treated at our institution. In each case, the latency period from irradiation to the development of each RIS and the median overall survival (OS) of the patients was analysed by Kaplan-Meier analysis. Spearman's correlation test was used to determine the relationship between the latency period and radiation dose or age at irradiation. RESULTS: The mean age at the development of RIS was 39.63 ± 17.84 years. The mean latency period was 11.79 ± 8.09 years. No factors associated with early development of RIS were detected. The median OS was 11 months, with fibrosarcoma showing significantly shorter OS compared with osteosarcoma and other sarcomas (p = 0.0021), and intracranial RIS showing a worse prognosis than extracranial RIS (p < 0.0001). Patients treated with surgery (p < 0.0001) and postoperative chemotherapy (p = 0.0157) for RIS presented significantly longer OS, whereas RT for RIS was not associated with a survival benefit. CONCLUSIONS: Although prognosis for RIS is universally poor, pathological characteristics and locations are associated with worse prognosis. Surgery and chemotherapy may be the ideal treatment strategies for RIS.

Multidrug chemotherapy, whole-brain radiation and cytarabine therapy for primary central nervous system lymphoma in elderly patients with dose modification based on geriatric assessment: study protocol for a phase II, multicentre, non-randomised study.

INTRODUCTION: Multidrug chemoimmunotherapy with rituximab, high-dose methotrexate, procarbazine and vincristine (R-MPV) is a standard therapy for younger patients with primary central nervous system lymphoma (PCNSL); however, prospective data regarding its use in elderly patients are lacking. This multi-institutional, non-randomised, phase II trial will assess the efficacy and safety of R-MPV and high-dose cytarabine (HD-AraC) for geriatric patients with newly diagnosed PCNSL. METHODS AND ANALYSIS: Forty-five elderly patients will be included. If R-MPV does not achieve complete response, the patients will undergo reduced-dose, whole-brain radiotherapy comprising 23.4 Gy/13 fractions, followed by local boost radiotherapy comprising 21.6 Gy/12 fractions. After achieving complete response using R-MPV with or without radiotherapy, the patients will undergo two courses of HD-AraC. All patients will undergo baseline geriatric 8 (G8) assessment before HD-AraC and after three, five and seven R-MPV courses. Patients with screening scores of ≥14 points that decrease to <14 points during subsequent treatment, or those with screening scores <14 points that decrease from the baseline during subsequent treatment are considered unfit for R-MPV/HD-AraC. The primary endpoint is overall survival, and the secondary endpoints are progression-free survival, treatment failure-free survival and frequency of adverse events. The results will guide a later phase III trial and provide information about the utility of a geriatric assessment for defining chemotherapy ineligibility. ETHICS AND DISSEMINATION: This study complies with the latest Declaration of Helsinki. Written informed consent will be obtained. All participants can quit the study without penalty or impact on treatment. The protocol for the study, statistical analysis plan and informed consent form have been approved by the Certified Review Board at Hiroshima University (CRB6180006) (approval number: CRB2018-0011). The study is ongoing within nine tertiary and two secondary hospitals in Japan. The findings of this trial will be disseminated through national and international presentations and peer-reviewed publications. TRIAL REGISTRATION: jRCTs061180093.

Secondary meningioma after cranial irradiation: case series and comprehensive literature review.

BACKGROUND: Secondary meningioma after cranial irradiation, so-called radiation-induced meningioma, is one of the important late effects after cranial radiation therapy. In this report, we analyzed our case series of secondary meningioma after cranial irradiation and conducted a critical review of literature to reveal the characteristics of secondary meningioma. MATERIALS AND METHODS: We performed a comprehensive literature review by using Pubmed, MEDLINE and Google scholar databases and investigated pathologically confirmed individual cases. In our institute, we found pathologically diagnosed seven cases with secondary meningioma between 2000 and 2018. Totally, 364 cases were analyzed based on gender, WHO grade, radiation dose, chemotherapy. The latency years from irradiation to development of secondary meningioma were analyzed with Kaplan-Meier analysis. Spearman's correlation test was used to determine the relationship between age at irradiation and the latency years. RESULTS: The mean age at secondary meningioma development was 35.6 ± 15.7 years and the mean latency periods were 22.6 ± 12.1 years. The latency periods from irradiation to the development of secondary meningioma are significantly shorter in higher WHO grade group (P = 0.0026, generalized Wilcoxon test), higher radiation dose group (P < 0.0001) and concomitant systemic chemotherapy group (P = 0.0003). Age at irradiation was negatively associated with the latency periods (r = -0.23231, P < 0.0001, Spearman's correlation test). CONCLUSION: Cranial irradiation at older ages, at higher doses and concomitant chemotherapy was associated with a shorter latency period to develop secondary meningiomas. However, even low-dose irradiation can cause secondary meningiomas after a long latency period. Long-term follow-up is necessary to minimize the morbidity and mortality caused by secondary meningioma after cranial irradiation.

Epstein-barr Virus Negative Primary Central Nervous System Lymphoma Developed after Treatment of Glioblastoma: A Case Report.

Temozolomide is an oral alkylating agent with moderate side effects compared to other agents. However, the development of secondary malignancies following temozolomide has been reported. We describe the first case of primary central nervous system lymphoma (PCNSL) occurrence following glioblastoma treatment. A 69-year-old male was admitted to our hospital with a chief complaint of headache and dysnomia for six months. A ring-enhanced mass of the left temporal lobe was observed and gross total removal was performed. The tumor was pathologically diagnosed as isocitrate dehydrogenase (IDH)-wildtype glioblastoma and he received 60 Gy of local irradiation in 30 fractions, with concurrent temozolomide at a dose of 75 mg/m2. Grade 2 lymphopenia was discovered during treatment. Within 6 months, the patient developed a right parietal intra-axial tumor without local recurrence and was given 150-200 mg/m2 oral temozolomide for five consecutive days of a 28-day cycle. Within five cycles of temozolomide, complete remission was observed; however, after the eighth cycle, a new lesion in the right temporal lobe was discovered. Surgical removal was performed and histological findings were consistent with diffuse large B-cell lymphoma, and the final diagnosis of Epstein-Barr virus negative PCNSL was established.

Influence of growth hormone therapy on germinoma survivors.

PURPOSE: Due to the effectiveness of growth hormone therapy (GHT), the number of cancer survivors receiving GHT has increased. Previous studies had indicated that GHT was not associated with the increasing risks of tumor recurrence and development with second neoplasm (SN) in cancer survivors. However, to date, research on those risks in germinoma survivors is still limited. The aim of this study is to evaluate the impact of GHT in relation to tumor recurrence and development with SN in pure germinoma survivors. METHODS: This retrospective cohort study was approved by the Ethical Committee for Epidemiology of our institution. Seventy-three consecutive patients who underwent a biopsy of the lesion and were diagnosed with pure germinoma were retrospectively studied. They (median age, 15.0 years) were followed up more than 1 year after biopsy (median follow-up period, 14.3 years). The following data was obtained from the medical records of the patients: age, sex, preoperative magnetic resonance imaging findings, hormonal replacement, and events including tumor recurrence and/or SN. RESULTS: In our patient series, 16 patients (21.9%) who were more likely to have neurohypophysial lesion and receive multiple hormonal therapies had received GHT. No significant differences in the rates of tumor recurrence and development with SN were observed between the patients who had and had not received GHT. Moreover, the recurrence-free survival and overall survival rates were not different between the patients who had and had not received GHT. CONCLUSIONS: GHT did not increase the risks of tumor recurrence and development with SN in pure germinoma survivors.

Characteristics and therapeutic strategies of radiation-induced glioma: case series and comprehensive literature review.

INTRODUCTION: The so-called radiation-induced glioma (RIG, a secondary glioma after cranial irradiation), is a serious late effect after cranial radiation therapy. The clinical characteristics of and ideal treatment for these tumors are unclear. We analyzed our case series and conducted a comprehensive literature review to reveal the precise characteristics of RIGs. METHODS: We analyzed the cases of six patients with RIGs treated at our institution and 354 patients with RIGs from the literature. The latency period from irradiation to the development of each RIG and the median overall survival of the patients were subjected to Kaplan-Meier analyses. Spearman's correlation test was used to determine the relationship between age at irradiation and the latency period. RESULTS: The mean age of the 360 patients at the development of RIG was 27.42 ± 17.87 years. The mean latency period was 11.35 ± 8.58 years. Multiple gliomas were observed in 28.4%. WHO grade 3 and 4 RIGs accounted for 93.3%. The latency periods were significant shorter in the higher WHO grade group (p = 0.0366) and the concomitant systemic chemotherapy group (p < 0.0001). Age at irradiation was negatively associated with the latency period (r =- 0.2287, p = 0.0219). The patients treated with radiotherapy achieved significantly longer survival compared to those treated without radiotherapy (p = 0.0011). CONCLUSIONS: Development in younger age, multiplicity, and high incidence of grade 3 and 4 are the clinical characteristics of RIGs. Cranial irradiation at older ages and concomitant chemotherapy were associated with shorter latency for the development of RIG. Radiation therapy may be the feasible treatment option despite radiation-induced gliomas.

[Astroblastoma with Rapid Cyst Expansion and Hemorrhage in an Adult: A Case Report].

Astroblastoma is an extremely rare primary brain tumor accounting for 0.45 to 2.8% of all neuroglial tumors and usually occurs in pediatrics and young adults. The natural history of astroblastoma still remains unknown. In the World Health Organization (WHO) classification of tumors of the central nervous system, astroblastoma is classified as other neuroepithelial tumors and standard treatment other than surgery has not been established. As molecular and genetic diagnosis becomes more important in the latest WHO classification of brain tumors, the development of therapeutic options based on the information of molecular genetics are expected. Here we report a case of astroblastoma in a 49-year-old male. Small tumor was discovered by coincidence during his check-up following traffic accident, but three months later, tumor bleeding with cystic enlargement resulted in disturbance of consciousness. Initial diagnosis of low grade astroblastoma with BRAFV600E mutation was made. After 1 year, local tumor recurrence was observed. The histological diagnosis at recurrence was high grade astroblastoma. We here, discuss about diagnosis, treatment and the possibility of usefulness of molecular genetic analysis for astroblastoma with some literature review. (Received 10 August, 2021; Accepted 15 December, 2021; Published 1 April, 2022).

[Craniopharyngioma Mimicking Chordoid Glioma].

Entirely intrinsic third ventricular craniopharyngiomas showed characteristics of a round/oval shaped tumor, with rare calcification and cyst formation, and pathologically squamous-papillary type with a positive BRAFV600E mutation. We report an extremely rare case of entirely intrinsic third ventricular craniopharyngioma, pathologically adamantiomatous but with BRAFV600E mutation genetically, developed in a 35-year-old female. It was oval-shaped, with no calcification or cyst, and showed homogeneous enhancement. As shown in this case, it was difficult to differentiate this pathology from chordoid glioma of third ventricle, and the difficulty of this differential diagnosis has not been well documented in previous studies. Our case further implied the importance of molecular diagnosis for subclassification of craniopharyngioma. The BRAFV600E-mutated craniopharyngioma could be the target for the development of treatment with preoperative BRAF-inhibitors. Therefore, differentiation between entirely intrinsic third ventricular craniopharyngiomas and chordoid glioma could be new issue. In this report, we discuss about the preoperative differential diagnosis from chordoid glioma and the literature review. (Received 12 August, 2021; Accepted 21 September, 2021; Published 1 February, 2022).

Diffusion-weighted imaging-gadolinium enhancement mismatch sign in diffuse midline glioma.

BACKGROUND: Diffuse midline glioma (DMG), H3 K27M-mutant including diffuse intrinsic pontine glioma (DIPG) is a disease with dismal prognosis. We focused on diffusion-weighted imaging (DWI) and gadolinium enhanced T1WI (Gd), especially high intensity on DWI at non-enhanced lesion, i.e. DWI-Gd mismatch sign, to establish as an imaging biomarker of DMG patients. MATERIALS AND METHODS: Our institutional review board approved this retrospective study. Twenty-one patients diagnosed as DMG including DIPG at our institution between 2007 and 2020 were enrolled in this study. All patients underwent local radiotherapy of 54 Gy/30 fractions. We studied the relationship between imaging features including DWI-Gd mismatch sign and prognosis. RESULTS: DWI-Gd mismatch sign was found in 9 out of 21 DMG patients. Among different imaging characteristics, existence of high intensity on DWI (P = 0.0014), gadolinium enhancement (P = 0.00071) were the significant poor prognostic markers in DMG, which were consistent with the previous reports about DIPG. In our results, positive DWI-Gd mismatch sign was statistically strongest poor prognostic imaging biomarker, and patients with positive DWI-Gd mismatch sign had shorter OS compared to those with negative mismatch sign (9.9 months vs 18.6 months, P = 0.00062). DWI/Gd mismatch sign and intratumoral bleeding were more common in DMG at thalamus compared to DMG at pons/DIPG (P = 0.046 and P = 0.0017, respectively). CONCLUSIONS: DWI-Gd mismatch sign may be an imaging biomarker for poor prognosis in DMG. (E-1601).

Intratumoral Hemorrhage After Endoscopic Third Ventriculostomy for Obstructive Hydrocephalus Caused by Brain Tumors.

BACKGROUND: Endoscopic third ventriculostomy (ETV) for obstructive hydrocephalus and endoscopic biopsy (EB) for intraventricular and paraventricular tumors are standard therapies because they are minimally invasive procedures. Although EB-associated hemorrhagic risk has been well documented, there have been only a few reports on hemorrhagic risk associated with ETV. We conducted a single-institution retrospective study on the incidence of hemorrhage secondary to EB and/or ETV. METHODS: We retrospectively reviewed patient characteristics, procedure, pathological findings, and complications including hemorrhage of 100 patients with intraventricular and paraventricular tumors who underwent EB and/or ETV at our institution from 2000 to 2020. RESULTS: EB/ETV combined surgery (combined group), EB-alone surgery (EB-alone group), and ETV-alone surgery (ETV-alone group) were performed in 44 (44%), 24 (24%), and 32 (32%) patients, respectively, and all procedures were successful. The rates of definitive and suggestive diagnoses in EB were 76.5% and 23.5%, respectively. Adverse events were observed in 6 patients. In the combined group, acute obstruction of the ETV stoma was observed in 1 patient and transient double vision was observed in 1 patient. Transient aqueductal stenosis/obstruction was observed in 2 patients in the EB-alone group. In the ETV-alone group, hemorrhage was observed in 2 patients; these patients developed intratumoral hemorrhage despite ETV-alone surgery. Subsequently, these 2 patients underwent tumor removal, and the histopathological diagnosis was atypical teratoid/rhabdoid tumor in both. CONCLUSIONS: For obstructive hydrocephalus with atypical teratoid/rhabdoid tumor, physicians must be aware of the risk of postoperative intratumoral hemorrhage after performing ETV.

T2-FLAIR Mismatch Sign and Response to Radiotherapy in Diffuse Intrinsic Pontine Glioma.

PURPOSE: The T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign was previously reported as a diagnostic indicator of diffuse astrocytoma, isocitrate dehydrogenase-mutant, and 1p/19q noncodeletion. Subsequently, it was reported that the same findings were observed in diffuse intrinsic pontine glioma (DIPG). We investigated the clinical significance of T2-FLAIR mismatch sign in DIPG. METHODS: Twenty-one patients with DIPG (Male: Female = 12:9) were treated at our institute between 2004 and 2019. All patients were treated with local radiotherapy of 54 Gy/30 fractions. The positive T2-FLAIR mismatch sign was defined if it fulfilled the following criteria: (1) T2-FLAIR mismatch volume was >50% of T2 high volume at nonenhanced area, (2) the FLAIR low lesion is not associated with gadolinium enhancement (inside of enhancement or just outside of enhancement defined as edema), and (3) signal-intensity of FLAIR lowest lesion at tumor is lower than the normal cerebellar cortex. RESULTS: In our patient series, T2-FLAIR mismatch sign was found in 5 out of 21 patients. Objective response rate of radiotherapy was 100% in patients positive for T2-FLAIR mismatch, while it was 25.0% in patients negative for T2-FLAIR mismatch, and this difference was statistically significant (p < 0.01, Fisher's exact test). In patients under the age of 18-years, T2-FLAIR mismatch positive had a slightly better prognosis (p < 0.05, Wilcoxon test). CONCLUSION: T2-FLAIR mismatch sign in DIPG may be an indicator for better response to radiotherapy and a better prognostic factor.

Detecting non-germinomatous germ cell tumor component by arterial spin labeling perfusion-weighted MR imaging in central nervous system germ cell tumor.

PURPOSE: Differentiating between germinoma and non-germinomatous germ cell tumor (NGGCT) is important because sensitivity to chemotherapy and/or radiotherapy is quite different between these two subgroups. In this study, we evaluated whether the arterial spin labeling (ASL) based perfusion-weighted imaging (PWI) could provide additional information for the differential diagnosis between germinoma and NGGCT. METHOD: Between 2011 and 2018, 20 patients with central nervous system (CNS) germ cell tumor (GCT) who underwent preoperative MR imaging including ASL-PWI were enrolled in this study. Relative tumor blood flow (rTBF) was evaluated on ASL-PWI by manually placing regions of interest at gadolinium enhanced part of the tumors and normal subcortical white matter. Presence of intratumoral T1 hyperintense foci and apparent diffusion coefficient (ADC) were also evaluated. The final diagnosis was made by the combination of tumor markers and the histological diagnosis. RESULTS: Among 20 patients of CNS-GCT, 11 were diagnosed as germinoma and 9 were diagnosed as NGGCT. In the germinoma subgroup, the rTBF ranged from 0.90 to 1.71 (mean 1.21, median 1.09), while it ranged from 1.14 to 5.75 (mean 3.91, median 3.31) in NGGCT subgroup. The receiver operating characteristic (ROC) curve showed that calculating rTBF is useful for differentiating between germinoma and NGGCT (area under the curve (AUC) 0.929, P = 0.0012) compared to intratumoral T1 hyperintense foci (AUC 0.788, P = 0.0304) and ADC (AUC 0.919, P = 0.0016). CONCLUSIONS: High rTBF obtained by ASL-PWI implied the presence of NGGCT component. This information might help in deciding the chemotherapy/radiotherapy intensity.

Radiology Profile as a Potential Instrument to Differentiate Between Posterior Fossa Ependymoma (PF-EPN) Group A and B.

OBJECTIVE: Posterior fossa ependymoma (PF-EPN) was categorized into PF-EPN-A and PF-EPN-B subgroups based on the DNA methylation profiling. PF-EPN-A was reported to have poorer prognosis compared with PF-EPN-B. In this study, we particularly evaluated preoperative imaging to distinguish PF-EPN-A from PF-EPN-B. METHODS: Sixteen cases of PF-EPN were treated in our institution from 1999 to 2018. The patients were divided into PF-EPN-A and PF-EPN-B groups based on H3K27me3 immunostaining positivity. We evaluated progression-free survival, overall survival, as well as preoperative magnetic resonance imaging and computed tomography scan images in both groups. Based on T1WI and Gd-T1WI magnetic resonance images, the tumor contrast rate was determined from dividing the volume of gadolinium enhanced tumor by the overall tumor volume. RESULTS: Nine cases (4 male, 5 female) were grouped as PF-EPN-A, and 7 (4 male, 3 female) as PF-EPN-B. The median age of PF-EPN-A and PF-EPN-B were 4 and 43 years old, respectively. In the PF-EPN-A group, the progression-free survival median value was 32.6 months, and the overall survival median was 96.9 months. In contrast, PFS in PF-EPN-B did not reach a median value (P < 0.05) and all the patients were alive (P < 0.05) at the end of the study. With imaging, tumor contrast rate in PF-EPN-B was more than 50% and significantly different from PF-EPN-A (P = 0.0294). Calcification was mainly observed in PF-EPN-A, whereas cystic formation was only seen in PF-EPN-B. CONCLUSIONS: Contrast rate less than 50%, based on the magnetic resonance images, was characteristic in the PF-EPN-A group. Comparatively, cystic component and absence of calcification were more characteristic in the PF-EPN-B group.

Advantage of high b value diffusion-weighted imaging for differentiation of common pediatric brain tumors in posterior fossa.

PURPOSE: The pediatric posterior fossa (PF) brain tumors with higher frequencies are embryonal tumors (ET), ependymal tumors (EPN) and pilocytic astrocytomas (PA), however, it is often difficult to make a differential diagnosis among them with conventional MRI. The ADC calculated from DWI could be beneficial for diagnostic work up. METHOD: We acquired DWI at b = 1000 and 4000(s/mm2). The relationship between ADC and the three types of brain tumors was evaluated with Mann-Whitney U test. We also performed simple linear regression analysis to evaluate the relationship between ADC and cellularity, and implemented receiver operating characteristic curve (ROC curve) to test the diagnostic performance among tumors. RESULTS: The highest ADC (b1000/b4000 × 10-3 mm2/s) was observed in PA (1.02-1.91/0.73-1.28), followed by PF-EPN (0.83-1.28/0.60-0.79) and the lowest was ET (0.41-0.75/0.29-0.47). There was significant difference among the groups in both ADC value (b-1000/b-4000: ET vs. PF-EPN p < 0.0001/0.0001, ET vs. PA p < 0.0001/0.0001, PF-EPN vs. PA p < 0.0001/0.0001). ROC analysis revealed that ADC in both b-values showed complete separation between ET and PF-EPN. And it also revealed that ADC at b-4000 could differentiate PF-EPN and PA (96.0%) better than ADC at b-1000 (90.1%). The stronger negative correlation was observed between the ADC and cellularity at b-4000 than at b-1000 (R2  = 0.7415 vs.0.7070) CONCLUSIONS: ADC of ET was significantly lower than the other two groups, and ADC of PA was significantly higher than the other two groups in both b-1000 and b-4000. Our results showed that ADC at b-4000 was more useful than ADC at b-1000 especially for differentiation between PF-EPN and PA.

T2-FLAIR mismatch sign in dysembryoplasticneuroepithelial tumor.

PURPOSE: T2-FLAIR mismatch sign was reported as specific imaging marker in non-enhancing diffuse astrocytoma, IDH-mutant & 1p/19q non-codeleted. However, most of the previous studies for T2-FLAIR mismatch sign were confirmed only among lower grade glioma. The aim of this study is to assess the T2-FLAIR mismatch sign in dysembryoplastic neuroepithelial tumor (DNET) and unveil the exception rules of the sign. METHOD: Eleven patients with histopathologically confirmed DNET were included in this study. The MR images were evaluated by 2 independent reviewers to assess (i) the presence or absence of T2-FLAIR mismatch sign and (ii) the presence or absence of gadolinium enhancement. CT was also performed to evaluate calcification and localized thinning of the skull bone. Inter-reviewer agreement with Cohen's kappa (κ) was calculated. RESULTS: The T2-FLAIR mismatch sign was present in 8 cases (72.7 %) and absent in 3 cases (27.3 %). None of them showed contrast enhancement on initial MR images. The inter-reviewer agreement for T2-FLAIR mismatch and CT characteristics was excellent (κ = 1.00). All of the DNET without T2-FLAIR mismatch presented with calcification on CT. All of the DNET adjacent to skull vault (5 cases) presented with localized bone thinning overlying the tumor. CONCLUSIONS: The T2-FLAIR mismatch sign was observed in more than half of the DNET and the sign is not specific for diffuse astrocytoma, IDH-mutant & 1p19q non-codeleted. The localized skull bone thinning overlying the tumor might help for diagnosis of DNET in some cases.

Bevacizumab for optic pathway glioma with worsening visual field in absence of imaging progression: 2 case reports and literature review.

Children with optic pathway gliomas (OPGs) frequently suffer from problems of visual function resulting from tumors. Previous reports showed that bevacizumab improved visual function in patients with OPG via tumor response to treatment. In these two case reports, we show that bevacizumab improved visual field without tumor response as seen in imaging. Both, a 10-year-old girl and a 6-year-old boy, had previous history of treatment with platinum-based chemotherapy. They had visual deterioration without tumor progression on MR imaging. Bevacizumab effectively and immediately improved visual field in both patients without imaging response of OPG. We emphasize that bevacizumab should be considered for patients with OPGs having visual deterioration without tumor progression.

Primary and Recurrent Growing Teratoma Syndrome in Central Nervous System Nongerminomatous Germ Cell Tumors: Case Series and Review of the Literature.

BACKGROUND: The term "growing teratoma syndrome (GTS)" has been used as follows: patients with germ cell tumor (GCT) who present with enlarging original/metastatic masses during or after appropriate systemic chemotherapy despite normalized serum markers. In other words, the definition of the term GTS is not fully established. We analyzed and reviewed our case series regarding GTS that developed after the treatment of central nervous system (CNS) nongerminoatous germ cell tumors (NGGCTs). METHODS: Our institutional review board approved this retrospective study. Between 2003 and 2018, we treated 16 patients (16 males; age ranging from 5.4 to 51.9 years, median 13.8) with CNS-NGGCT at our institution. We reviewed those patients and also reviewed the literature about GTS of CNS. We defined primary GTS (p-GTS) as the enlargement of cyst size and/or solid tumor occurred during treatment in the absence of marker elevation, and recurrent GTS (r-GTS) as the enlargement of teratoma after complete response of initial tumors. RESULTS: Among 16 patients with CNS-NGGCT, we surgically confirmed mature/immature teratoma components in 15 patients. Two patients underwent surgical removal of tumor before neoadjuvant therapy, and among the rest 14 patients, 6 developed p-GTS, and 2 patients underwent salvage surgery during chemo-/chemoradiotherapy. Those with histologic diagnosis of immature teratoma during salvage surgery had a shorter interval from the initiation of chemoradiotherapy compared with mature teratoma (P < 0.05). One patient developed r-GTS. In the literature review, most of the p-GTS consisted of enlargement with the multicystic component. Histologic diagnosis of immature teratoma during salvage surgery was observed in earlier stages of chemoradiotherapy (P < 0.05, log-rank test). Previous history of p-GTS might be a risk factor of r-GTS. CONCLUSIONS: The incidence of p-GTS, enlargement of the cystic component during treatment, is not rare. Physicians need to be aware of this important phenomenon.