HGG-11. LEPTOMENINGEAL DISEASE AND TUMOR DISSEMINATION ALONG CSF PATHWAYS IN A MURINE DIPG MODEL: IMPLICATIONS FOR STUDY OF THE TUMOR-CSF-EPENDYMAL MICROENVIRONMENT

Background Leptomeningeal disease and hydrocephalus are present in up to 30% of patients with diffuse intrinsic pontine glioma (DIPG), however there are no animal models of cerebrospinal fluid (CSF) dissemination. As the tumor-CSF-ependymal microenvironment may play an important role in tumor pathogenesis, we identified characteristics of the Nestin-tumor virus A (Nestin-Tva) genetically engineered mouse model (GEMM) that make it ideal to study the interaction of tumor cells with the CSF and its associated pathways with implications for the development of treatment approaches to address CSF dissemination in DIPG. Methods A Nestin-TVa model of DIPG utilizing the three most common DIPG genetic alterations (H3.3K27M, PDGF-B, p53) was used for this study. All animals underwent MR imaging and a subset underwent histopathologic analysis with H&E and beta-IV tubulin. Results Tumor dissemination within the CSF pathways (ventricles, leptomeninges) was present in 76% (25/33) of animals, with invasion of the choroid plexus, disruption of the ciliated ependyma and regional subependymal fluid accumulation. Ventricular enlargement consistent with hydrocephalus was present in 94% (31/33). Ventricle volume correlated with region specific transependymal CSF flow (periventricular T2 signal), localized anterior to the lateral ventricles. Subependymal tumor cells were also present subjacent to the 4th ventricle in a post-mortem human specimen. Conclusions This is the first study to report CSF pathway tumor dissemination an animal model of DIPG and is representative of CSF dissemination seen clinically. Understanding the CSF-tumor-ependymal microenvironment has significant implications for treatment of DIPG through targeting mechanisms of tumor spread within the CSF pathways.

Clinical-MRI radiomics enables the prediction of preoperative cerebral spinal fluid dissemination in children with medulloblastoma

Background Medulloblastoma (MB) is the most common pediatric embryonal tumor. Accurate identification of cerebral spinal fluid (CSF) dissemination is important in prognosis prediction. Both MRI of the central nervous system (CNS) and CSF cytology will appear false positive and negative. Our objective was to investigate the added value of preoperative-enhanced T1-weighted image-based radiomic features to clinical characteristics in predicting preoperative CSF dissemination for children with MB. Materials and methods This retrospective study included 84 children with histopathologically confirmed MB between November 2006 and November 2018 (training cohort, n=60; internal validation cohort, n=24). A set of cases between December 2018 and February 2020 were used for external validation (n=40). The children with normal head and spine magnetic resonance images (MRI) and no subsequent dissemination in 1 year were diagnosed as non-CSF dissemination. The CSF dissemination was manifested as intracranial or intraspinal nodular-enhanced lesions. Clinical features were collected, and conventional MRI features of preoperative head MRI examinations were evaluated. A total of 385 radiomic features were extracted from preoperative-enhanced T1-weighted images. Minimum redundancy, maximum correlation, and least absolute shrinkage and selection operator were performed to select the features with the best performance in predicting preoperative CSF dissemination. A combined clinical-MRI radiomic prediction model was developed using multivariable logistic regression. Receiver operating curve analysis (ROC) was used to validate the predictive performance. Nomogram and decision curve analysis (DCA) were developed to evaluate the clinical utility of the combined model. Results One clinical and nine radiomic features were selected for predicting preoperative CSF dissemination. The combined model incorporating clinical and radiomic features had the best predictive performance in the training cohort with an AUC of 0.89. This was validated in the internal and external cohorts with AUCs of 0.87 and 0.73. The clinical utility of the model was confirmed by a clinical-MRI radiomic nomogram and DCA. Conclusions The combined model incorporating clinical, conventional MRI, and radiomic features could be applied to predict preoperative CSF dissemination for children with MB as a noninvasive biomarker, which could aid in risk evaluation.

Clinical-MRI Radiomics Enables the Prediction of Preoperative Cerebral Spinal Fluid Dissemination in Children With Medulloblastoma

Background: Medulloblastoma (MB) is the most common pediatric embryonal tumor. Accurate identification of cerebral spinal fluid (CSF) dissemination is important in prognosis prediction. Both MRI of the central nervous system (CNS) and CSF cytology will appear false positive and negative. Our objective was to investigate the added value of enhanced T1 weighted images-based radiomics features to clinical characteristics in predicting preoperative CSF dissemination for children with MB.Materials and Methods: This retrospective study included 84 children with histopathologically confirmed MB (60 children in the training cohort and 24 children in the validation cohort). The children with normal head and spine magnetic resonance images (MRI) and no subsequent dissemination in one year were diagnosed as non-CSF dissemination. The CSF dissemination was manifested as intra-cranial or -spinal nodular enhanced lesions. Clinical features and conventional MRI features were collected and evaluated. A total of 385 radiomics features were extracted from enhanced T1 weighted images. Minimum redundancy, maximum correlation and least absolute shrinkage and selection operator were performed to select the features with the best performance in predicting preoperative CSF dissemination. A combined clinical-MRI radiomics prediction model was developed using multivariable logistic regression. Receiver operating curve analysis was used to validate the predictive performance. Nomogram and decision curve analysis (DCA) were developed to evaluate the clinical utility of combined model.Results: Thirty-one children were confirmed to have preoperative CSF dissemination. One clinical and nine radiomics features were selected for predicting preoperative CSF dissemination. The combined model incorporating clinical and radiomics features had best predictive performance both in the training and validation cohorts. In the validation cohort, a threshold of 0.311 yielded an area under the curve of 0.87, a sensitivity of 77.8%, a specificity of 86.7%, and an accuracy of 83.3%. The clinical utility of the model was confirmed by a clinical-MRI radiomics nomogram and DCA. Conclusions: The combined model incorporating clinical, conventional MRI and radiomics features could be applied to predict preoperative CSF dissemination for children with MB as a noninvasive biomarker, which could aid in risk evaluation.

Minimal disseminated disease evaluation and outcome in trilateral retinoblastoma

Trilateral retinoblastoma (TRb) presents a management challenge, since intracranial tumours are seldom times resectable and quickly disseminate. However, there are no risk factors to predict the final outcome in each patient.ObjectiveTo evaluate minimal disseminated disease (MDD) in the bone marrow (BM) and the cerebrospinal fluid (CSF) at diagnosis and during follow-up and reviewing its potential impact in the outcome of patients with TRb.Methods and analysisWe evaluated MDD in five patients with TRb, detecting the mRNA of CRX and/or GD2, in samples from BM and CSF, obtained at diagnosis, follow-up and relapse.ResultsTreatment involved intensive systemic chemotherapy in four patients, one did not receive this treatment and died of progression of the disease. Two patients underwent stem cell rescue. Three patients had leptomeningeal relapse and died. One patient remains disease-free for 84 months. RB1 mutations were identified in the five patients, all of them were null mutations. At diagnosis, one patient had tumour cells in the CSF, and none had the BM involved. Only one case of four presented MDD during follow-up in the CSF, without concomitant detection in the BM. On leptomeningeal relapse, no case had MDD in the BM. In all these cases, cells in the CSF were positive for GD2 and/or CRX.ConclusionCSF dissemination always concluded in the death of the patient, without concomitant systemic dissemination denoting the importance of increasing treatment directed to the CSF compartment. The MDD presence could indicate a forthcoming relapse.

Microsurgical enbloc resection of myxopapillary cauda equina ependymoma

Benign myxopapillary filum terminale ependymomas are often poorly encapsulated and in apposition the cerebrospinal fluid (CSF). These characteristics present the potential surgical risk of CSF dissemination or injury to the delicate cauda equina nerve roots. This video details the techniques of en bloc surgical resection of a filum terminale ependymoma. Treatment strategies and techniques are illustrated to reduce the risk of CSF dissemination and cauda equina injury.The video can be found here: http://youtu.be/LK8AYg-5T7o.

Optic nerve seeding of atypical meningiomas presenting with subacute visual loss: 2 case reports with genetic characterization

Meningiomas rarely cause CSF dissemination, and CSF seeding to the optic nerve (ON) is extremely rare. This is the first report of 2 cases of atypical meningioma with subacute visual loss due to ON seeding. The authors present the genetic characteristics of these atypical meningiomas with CSF dissemination. The patient in Case 1 was a 36-year-old woman with a 1.5-cm mass within the left ON, and the patient in Case 2 was a 70-year-old woman with a 0.9-cm mass around the right ON. Both individuals had undergone multiple surgeries for primary lesions and local recurrent lesions. They presented with subacute visual loss, and both tumors were completely resected. The pathological diagnosis was atypical meningioma with high MIB-1 indices and p53-positive cell ratios in each case. Comparative genomic hybridization showed significant chromosomal copy number alterations similar to the results of previous surgeries, confirming that the tumors were disseminated lesions. The present findings suggest that genetic characteristics, such as 1p and 10qcen-23 losses and 17q and 20 gains, shared by the 2 cases might be associated with CSF dissemination of meningiomas.