Subependymomas Are Low-Grade Heterogeneous Glial Neoplasms Defined by Subventricular Zone Lineage Markers

Immunohistochemical analyses of neural stem cell lineage markers in normal feline brains and glial tumors

Neural stem cell (NSC) lineage cells have not been fully identified in feline brains, and the NSC-like nature of feline glial tumors has not been determined. In this study, 6 normal cat brains (3 newborn and 3 older cats) and 13 feline glial tumors were analyzed using immunohistochemical NSC lineage markers. The feline glial tumors were subjected to immunohistochemical scoring followed by hierarchical cluster analysis. In newborn brains, glial acidic fibrillary protein (GFAP)/nestin/sex-determining region Y-box transcription factor 2 (SOX2)-immunopositive NSCs, SOX2-immunopositive intermediate progenitor cells, oligodendrocyte transcription factor 2 (OLIG2)/platelet-derived growth factor receptor-α (PDGFR-α)-immunopositive oligodendrocyte precursor cells (OPCs), OLIG2/GFAP-immunopositive immature astrocytes, and neuronal nuclear (NeuN)/β-3 tubulin-immunopositive mature neuronal cells were observed. The apical membrane of NSCs was also immunopositive for Na+/H+ exchanger regulatory factor 1 (NHERF1). In mature brains, the NSC lineage cells were similar to those of the newborn brains. A total of 13 glial tumors consisted of 2 oligodendrogliomas, 4 astrocytomas, 3 subependymomas, and 4 ependymomas. Astrocytomas, subependymomas, and ependymomas were immunopositive for GFAP, nestin, and SOX2. Subependymomas and ependymomas showed dot-like or apical membrane immunolabeling for NHERF1, respectively. Astrocytomas were immunopositive for OLIG2. Oligodendrogliomas and subependymomas were immunopositive for OLIG2 and PDGFR-α. Feline glial tumors also showed variable immunolabeling for β-3 tubulin, NeuN, and synaptophysin. Based on these results, feline astrocytomas, subependymomas, and ependymomas appear to have an NSC-like immunophenotype. In addition, astrocytomas, subependymomas, and ependymomas have the characteristics of glial, oligodendrocyte precursor, and ependymal cells, respectively. Feline oligodendrogliomas likely have an OPC-like immunophenotype. In addition, feline glial tumors may have multipotential stemness for differentiation into neuronal cells. These preliminary results should be validated by gene expression analyses in future studies with larger case numbers.

Intraventricular Subependymoma With Obstructive Hydrocephalus: A Case Report and Literature Review

Subependymomas are benign tumors of the ventricles that grow from the ventricular wall into the cerebrospinal fluid spaces within the brain, obstructing the flow of the cerebrospinal fluid and causing obstructive hydrocephalus. It is estimated that ependymomas represent between 0.2% and 0.7% of all intracranial tumors. They arise most frequently in the fourth ventricle (50-60%) and the lateral ventricles (30-40%). We present the case of a 50-year-old patient, previously diagnosed with an intraventricular process, admitted in our clinic. At neurological examination, the patient was cooperative, bradylalic, and bradypsychic, with right hemiparesis, postural and balance disorders, and occasionally sphincteric incontinence. MRI with contrast described a left intraventricular tumor, in the frontal horn of the left lateral ventricle with homogeneous appearance, with a maximum diameter of 50 mm and base of insertion at the adjacent ependyma of the foramen of Monro, which determined obstructive hydrocephalus. Total resection of the left intraventricular cerebral tumor was achieved. Histopathological analysis revealed a subependymoma. Postoperative recovery was slowly favorable, with significant neurological improvement. At neurological examination at three-month follow-up, the patient's right hemiparesis and unsystematized balance disorders improved. A contrast-enhanced CT scan was performed, highlighting left frontal sequelae hypodensity corresponding to the operated tumor, enlarged left lateral ventricle without active hydrocephalus, and no sign of tumor recurrence. At six-month follow-up, clinico-radiologic findings coincide with those from three-month follow-up. Subependymomas are slow-growing (grade 1) tumors and generally have a favorable prognosis. Unfortunately, due to their anatomical level, multiple complications can arise, caused from obstructive hydrocephalus complications, such as cognitive dysfunction and incontinence. Tumor resection should be complete, a successful operation being a challenge for every neurosurgeon.

The Role of MRI in the Diagnosis of Spinal Cord Tumors

Spinal cord tumors are uncommon, and its multiple representatives not always have pathognomonic characteristics, which poses a challenge for both patients and caring physicians. The radiologist performs an important role in recognizing these tumors, as well as in differentiating between neoplastic and non-neoplastic processes, supporting clinical and surgical decision-making in patients with spinal cord injury. Magnetic Resonance Imaging (MRI) assessment, paired with a deep understanding of the various patterns of cord involvement allied to detailed clinical data can provide a diagnosis or significantly limit the differential diagnosis in most cases. In this article, we aim to review the most common and noteworthy intramedullary and extramedullary spinal tumors, as well as some other tumoral mimics, with an emphasis on their MRI morphologic characteristics.

Spinal Cord Subependymoma: A Subanalysis of the Neurospinal Society of Japan's Multicenter Study of Intramedullary Spinal Cord Tumors

OBJECTIVE

This study aimed to analyze the clinical characteristics, treatment strategies, and surgical outcomes of subependymoma patients from the 2022 Neurospinal Society of Japan multicenter intramedullary spinal cord tumor study.

METHODS

Twenty-six patients with spinal cord subependymoma who were included in the index study of 1,033 patients were retrospectively analyzed.

RESULTS

Mean patient age was 49.4 years. Seventeen patients were men and 9 were women. Sensory disturbance was reported in 22 patients and motor weakness in 18. Median duration of symptoms was 24 months. The tumor was eccentrically located in 19 patients (73.1%) and unilateral in 17 (65.4%). Gross total resection was achieved in 6 patients (23.1%). The same rate for ependymoma patients in the index study was significantly higher (74.8%). Median follow-up was 40.5 months (interquartile range, 18-68 months). In 2 patients who underwent only partial resection, reoperation was required owing to progression 68 and 90 months after surgery, respectively. No recurrence occurred in patients who underwent gross total resection. Five patients experienced neurological worsening after surgery.

CONCLUSION

Although spinal cord subependymoma can be difficult to distinguish from other intramedullary spinal cord lesions before surgery, it is characterized by an indolent clinical course and eccentric location. Surgical treatment should prioritize functional preservation because the prognosis is good even after subtotal resection.

Benign Glioma

Benign glioma broadly refers to a heterogeneous group of slow-growing glial tumors with low proliferative rates and a more indolent clinical course. These tumors may also be described as "low-grade" glioma (LGG) and are classified as WHO grade I or II lesions according to the Classification of Tumors of the Central Nervous System (CNS) (Louis et al. in Acta Neuropathol 114:97-109, 2007). Advances in molecular genetics have improved understanding of glioma tumorigenesis, leading to the identification of common mutation profiles with significant treatment and prognostic implications. The most recent WHO 2016 classification system has introduced several notable changes in the way that gliomas are diagnosed, with a new emphasis on molecular features as key factors in differentiation (Wesseling and Capper in Neuropathol Appl Neurobiol 44:139-150, 2018). Benign gliomas have a predilection for younger patients and are among the most frequently diagnosed tumors in children and young adults (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). These tumors can be separated into two clinically distinct subgroups. The first group is of focal, well-circumscribed lesions that notably are not associated with an increased risk of malignant transformation. Primarily diagnosed in pediatric patients, these WHO grade I tumors may be cured with surgical resection alone (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). Recurrence rates are low, and the prognosis for these patients is excellent (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). Diffuse gliomas are WHO grade II lesions with a more infiltrative pattern of growth and high propensity for recurrence. These tumors are primarily diagnosed in young adult patients, and classically present with seizures (Pallud et al. Brain 137:449-462, 2014). The term "benign" is a misnomer in many cases, as the natural history of these tumors is with malignant transformation and recurrence as grade III or grade IV tumors (Jooma et al. in J Neurosurg 14:356-363, 2019). For all LGG, surgery with maximal safe resection is the treatment of choice for both primary and recurrent tumors. The goal of surgery should be for gross total resection (GTR), as complete tumor removal is associated with higher rates of tumor control and seizure freedom. Chemotherapy and radiation therapy (RT), while not typically a component of first-line treatment in most cases, may be employed as adjunctive therapy in high-risk or recurrent tumors and in some select cases. The prognosis of benign gliomas varies widely; non-infiltrative tumor subtypes generally have an excellent prognosis, while diffusely infiltrative tumors, although slow-growing, are eventually fatal (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). This chapter reviews the shared and unique individual features of the benign glioma including diffuse glioma, pilocytic astrocytoma and pilomyxoid astrocytoma (PMA), subependymal giant cell astrocytoma (SEGA), pleomorphic xanthoastrocytoma (PXA), subependymoma (SE), angiocentric glioma (AG), and chordoid glioma (CG). Also discussed is ganglioglioma (GG), a mixed neuronal-glial tumor that represents a notable diagnosis in the differential for other LGG (Wesseling and Capper 2018). Ependymomas of the brain and spinal cord, including major histologic subtypes, are discussed in other chapters.

Clinical features and surgical outcomes of intracranial and spinal cord subependymomas

OBJECTIVE

Subependymomas are low-grade ependymal tumors whose clinical characteristics, radiographic features, and postsurgical outcomes are incompletely characterized due to their rarity. The authors present an institutional case series and a systematic literature review to achieve a better understanding of subependymomas.

METHODS

Adult patients with histologically confirmed subependymoma or mixed subependymoma-ependymoma surgically treated at a tertiary hospital between 1992 and 2020 were identified. A systematic literature review of the PubMed, Embase, Web of Science, and Google Scholar databases from inception until December 4, 2020, was conducted according to PRISMA guidelines. Data extracted from both groups included demographics, radiographic features, tumor characteristics, management, and follow-up variables.

RESULTS

Forty-eight unique patients with subependymoma were identified by chart review; of these patients, 8 (16.7%) had mixed subependymoma-ependymoma tumors. The median age at diagnosis was 49 years (IQR 19.8 years), and 26 patients (54.2%) were male. Forty-two patients (87.5%) had intracranial subependymomas, and 6 (12.5%) had spinal tumors. The most common presentation was headache (n = 20, 41.7%), although a significant number of tumors were diagnosed incidentally (n = 16, 33.3%). Among the 42 patients with intracranial tumors, 15 (35.7%) had hydrocephalus, and the most common surgical strategy was a suboccipital approach with or without C1 laminectomy (n = 26, 61.9%). Gross-total resection (GTR) was achieved in 33 cases (68.7%), and 2 patients underwent adjuvant radiotherapy. Most patients had no major postsurgical complications (n = 34, 70.8%), and only 1 (2.1%) had recurrence after GTR. Of 2036 reports initially identified in the systematic review, 39 were eligible for inclusion, comprising 477 patients. Of 462 patients for whom tumor location was reported, 406 (87.9%) were intracranial, with the lateral ventricle as the most common location (n = 214, 46.3%). Spinal subependymomas occurred in 53 patients (11.5%), with 3 cases (0.6%) in multiple locations. Similar to the case series at the authors' institution, headache was the most common presenting symptom (n = 231, 54.0%) among the 428 patients whose presentation was reported. Twenty-seven patients (6.3%) were diagnosed incidentally, and 36 cases (8.4%) were found at autopsy. Extent of resection was reported for 350 patients, and GTR was achieved in 250 (71.4%). Fifteen of 337 patients (4.5%) had recurrence or progression.

CONCLUSIONS

The authors' case series and literature review demonstrate that patients with subependymoma are well managed with resection and generally have a favorable prognosis.

Clinical independent prognostic factors and overall survival prognostic nomogram for intracranial subependymoma: A SEER population-based analysis 2004–2016

Purpose

This study was launched to ascertain the independent prognostic factors influencing the overall survival (OS) prognosis of intracranial subependymoma and construct a prognostic model to predict OS time.

Materials and methods

We collected data from patients with intracranial subependymoma, including treatment data, follow-up data, and clinical and pathological characteristics from the SEER database within 2004 to 2016, and patients were randomly classified into training and validation cohorts. Univariate and multivariate analyses were applied to the training group through building a Cox proportional hazards model. According to the results of multivariate analysis, we established a nomogram to forecast the OS rate of the per-case patient graphically, then calculated the accuracy of verification in both training and validation cohorts by concordance index (C-index). Univariate and multivariate analyses were used for different subgroups of unoperated versus operated, gross total resection (GTR), subtotal resection (STR), and biopsy after using the propensity score matching (PSM) analyses.

Results

A total of 667 patients were enrolled, and we randomly assigned 535 patients (80.21%) into the training cohort and 132 patients (19.79%) into the validation cohort. Age [hazard ratio (HR) = 6.355; 95% confidence interval (CI), 2.240–18.029; p = 0.001] and sex (HR = 0.475; 95% CI, 0.232–0.974; p = 0.042) were the independent prognostic factors in the training cohort. On the basis of age and sex, the nomogram was established to predict the OS for every patient (C-index = 0.733 ± 0.065 in the training cohort and 0.850 ± 0.065 in the validation cohort), and calibration plots reflected the reliability of the nomogram. Age, gender, or laterality was the independent prognostic factor for OS in the different matched subgroups of unoperated versus operated, GTR, STR, and biopsy. Surgical treatment, race, year of diagnosis, insurance, tumor location, tumor size, pathology, tumor grade, and radiation were not statistically significantly different in OS for subependymoma in our research.

Conclusion

Age and sex were the independent prognostic variables for OS in intracranial subependymoma. According to our research, we should not be more inclined to choose conservative or surgical treatment. Nonetheless, the information that we present might be useful to suggest potential hypotheses to be tested in the clinical research setting.

Thoracic low grade glial neoplasm with concurrent H3 K27M and PTPN11 mutations

We present the case of a 41-year-old man who developed worsening mid-thoracic back pain and imaging revealed a well-circumscribed intramedullary tumor in the thoracic spinal cord. Subtotal resection was performed, and histopathological analysis showed a cytologically bland, minimally proliferative glial neoplasm. Sequencing revealed H3 K27M and an activating PTPN11 mutation. Serial imaging revealed slow tumor regrowth over a three year period which prompted a second resection. The recurrent tumor displayed a similar low grade-appearing histology and harbored the same H3 K27M and PTPN11 mutations as the primary. While the prognostic importance of isolated H3 K27M in spinal gliomas is well-known, the combination of these two mutations in spinal low grade glioma has not been previously reported. Importantly, PTPN11 is a component of the MAPK signaling pathway. Thus, as building evidence shows that low grade-appearing gliomas harboring H3 K27M mutations along with BRAF or FGFR1 mutations have a relatively more favorable course compared to isolated H3 K27M-mutant midline gliomas, the present case provides new evidence for the prognostic importance of activating mutations in other components of the MAPK signaling pathway. This case further highlights the importance of clinico-radio-pathologic correlation when incorporating evolving genetic data into the integrated diagnosis of rare neuroepithelial tumors.

Step-by-Step Guide on How to Make a 2-Dimensional Operative Neurosurgical Video: Microsurgical Resection of a Right Lateral Ventricle Subependymoma by an Anterior Interhemispheric Transcallosal Approach

BACKGROUND

Digital video recordings are increasingly used across various medical and surgical disciplines with advances in computer hardware and software technologies. The creation of high-quality surgical video footage requires a basic understanding of key technical considerations, together with creativity and sound aesthetic judgment. Online operative videos have become a core resource within neurosurgical education.

OBJECTIVE

To provide a step-by-step description for making operative videos using a video from a real case as an example.

METHODS

We recorded an operative video of the microsurgical resection of a right lateral ventricle subependymoma performed by an anterior interhemispheric transcallosal approach. The patient consented to surgical resection of the subependymoma and to publication of this operative video. With the video, we explain the step-by-step process the authors used for developing the raw video into a publishable surgical video.

RESULTS

The patient depicted in our video tolerated the surgery well and made a complete recovery. The final video produced from the surgery illustrated elements that Operative Neurosurgery, Neurosurgery, and other journals require in surgical videos.

CONCLUSION

Although more than 1200 peer-reviewed (PubMed) neurosurgical operative videos have been published so far, there has not been a single publication that describes the step-by-step process of producing an operative video. To the best of our knowledge, this is the first published detailed description of editing of an educational operative video in neurosurgery and the first video case report of a microsurgical resection of subependymoma of the lateral ventricle in the peer-reviewed English literature.

Imaging characteristics of 4th ventricle subependymoma

PURPOSE

Subependymomas located within the 4th ventricle are rare, and the literature describing imaging characteristics is sparse. Here, we describe the clinical and radiological characteristics of 29 patients with 4th ventricle subependymoma.

METHODS

This is a retrospective multi-center study performed after Institutional Review Board (IRB) approval. Patients diagnosed with suspected 4th ventricle subependymoma were identified. A review of clinical, radiology, and pathology reports along with magnetic resonance imaging (MRI) images was performed.

RESULTS

Twenty-nine patients, including 6 females, were identified. Eighteen patients underwent surgery with histopathological confirmation of subependymoma. The median age at diagnosis was 52 years. Median tumor volume for the operative cohort was 9.87 cm³, while for the non-operative cohort, it was 0.96 cm³. Thirteen patients in the operative group exhibited symptoms at diagnosis. For the total cohort, the majority of subependymomas (n = 22) were isointense on T1, hyperintense (n = 22) on T2, and enhanced (n = 24). All tumors were located just below the body of the 4th ventricle, terminating near the level of the obex. Fourteen cases demonstrated extension of tumor into foramen of Magendie or Luschka.

CONCLUSION

To the best of our knowledge, this is the largest collection of 4th ventricular subependymomas with imaging findings reported to date. All patients in this cohort had tumors originating between the bottom of the body of the 4th ventricle and the obex. This uniform and specific site of origin aids with imaging diagnosis and may infer possible theories of origin.

Molecular Classification and Therapeutic Targets in Ependymoma

Ependymoma is a biologically diverse tumor wherein molecular classification has superseded traditional histological grading based on its superior ability to characterize behavior, prognosis, and possible targeted therapies. The current, updated molecular classification of ependymoma consists of ten distinct subgroups spread evenly among the spinal, infratentorial, and supratentorial compartments, each with its own distinct clinical and molecular characteristics. In this review, the history, histopathology, standard of care, prognosis, oncogenic drivers, and hypothesized molecular targets for all subgroups of ependymoma are explored. This review emphasizes that despite the varied behavior of the ependymoma subgroups, it remains clear that research must be performed to further elucidate molecular targets for these tumors. Although not all ependymoma subgroups are oncologically aggressive, development of targeted therapies is essential, particularly for cases where surgical resection is not an option without causing significant morbidity. The development of molecular therapies must rely on building upon our current understanding of ependymoma oncogenesis, as well as cultivating transfer of knowledge based on malignancies with similar genomic alterations.

Molecular Stratification of Childhood Ependymomas as a Basis for Personalized Diagnostics and Treatment

Ependymomas are among the most enigmatic tumors of the central nervous system, posing enormous challenges for pathologists and clinicians. Despite the efforts made, the treatment options are still limited to surgical resection and radiation therapy, while none of conventional chemotherapies is beneficial. While being histologically similar, ependymomas show considerable clinical and molecular diversity. Their histopathological evaluation alone is not sufficient for reliable diagnostics, prognosis, and choice of treatment strategy. The importance of integrated diagnosis for ependymomas is underscored in the recommendations of Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy. These updated recommendations were adopted and implemented by WHO experts. This minireview highlights recent advances in comprehensive molecular-genetic characterization of ependymomas. Strong emphasis is made on the use of molecular approaches for verification and specification of histological diagnoses, as well as identification of prognostic markers for ependymomas in children.

Tumor characteristics and surgical outcomes of intracranial subependymomas: a systematic review and meta-analysis

OBJECTIVE

The tumor characteristics and surgical outcomes of intracranial subependymomas are poorly defined. In this study the authors aimed to provide a comprehensive review of all clinical, pathological, radiological, and surgical aspects of this important neoplasm to inform future management strategies.

METHODS

A systematic review and meta-analysis of MEDLINE, EMBASE, Cochrane, and Google Scholar databases adherent to PRISMA guidelines was conducted.

RESULTS

Of the 1145 articles initially retrieved, 24 studies encompassing 890 cases were included. The authors identified 3 retrospective cohort studies and 21 case series, but no controlled trials. Mean age at presentation was 46.7 ± 18.1 years with a male predominance (70.2%). Common sites of tumor origin were the lateral ventricle (44.5%) and fourth ventricle (43.1%). Cumulative postoperative mortality and morbidity rates were 3.4% and 24.3% respectively. Meta-analysis revealed that male sex (HR 3.15, 95% CI 1.39-7.14, p = 0.006) was associated with poorer 5-year overall mortality rates. All-cause mortality rates were similar when performing subgroup meta-analyses for age (HR 0.50, 95% CI 0.03-7.36, p = 0.61), smaller subependymoma size (HR 1.51, 95% CI 0.78-2.92, p = 0.22), gross-total resection (HR 0.65, 95% CI 0.35-1.23, p = 0.18), and receipt of postoperative radiation therapy (HR 0.88, 95% CI 0.27-2.88, p = 0.84). Postoperative Karnofsky Performance Index scores improved by a mean difference of 1.62 ± 12.14 points (p = 0.42). The pooled overall 5-year survival rate was 89.2%, while the cumulative recurrence rate was 1.3% over a median follow-up ranging from 15.3 to 120.0 months. The pure subependymoma histopathological subtype was most prevalent (85.6%), followed by the mixed subependymoma-ependymoma tumor variant (13.7%).

CONCLUSIONS

Surgical extirpation without postoperative radiotherapy results in excellent postoperative survival and functional outcomes in the treatment of intracranial subependymomas. Aggressive tumor behavior should prompt histological reevaluation for a mixed subependymoma-ependymoma subtype. Further high-quality controlled trials are still required to investigate this rare tumor.

Intraparenchymal subependymoma: Case report and literature review

Background:

Intracranial subependymomas are rare slow-growing benign tumors typically located in the ventricular system, accounting for 0.07–0.7% of all intracranial neoplasms. Intraparenchymal subependymoma is extremely rare lesions, imposing a challenging diagnosis and management.

Case Description:

We describe a case of a supratentorial intraparenchymal mass on left occipital lobe in a 26-year-old woman with progressive headache and visual impairment. Differential diagnosis mainly included gliomas, neuronal-glial tumors, ependymoma, and subependymoma. Complete surgical resection was performed and histopathology analysis confirmed diagnosis of subependymoma. Despite its benign behavior the Ki67/MIB-1 labeling index assessed by immunohistochemistry was 5%. After 1 year of follow-up she was free of tumor recurrence.

Conclusion:

Intraparenchymal subependymoma is extremely rare tumors and literature review showed only 11 cases reported. In general, they are misdiagnosed as other tumors, so careful attention on clinical and radiological features must be taken when looking at a tumor close to the ventricular system, even though it does not have any obvious direct connection to it. Despite its benign nature, total removal must be attempted given that there are reports of recurrence, especially in partially removed tumors with high proliferation index. The role of adjuvant therapy is still limited and new treatment options are being developed as our knowledge on biological and molecular characteristics advances.

A rare case of intraparenchymal subependymoma in a child

Subependymoma is a slow-growing, exophytic, intraventricular glial neoplasm that commonly arises in the ventricular system. However, a report found that the frequency of intracerebral subependymoma was 0.4% in 1000 routine autopsies. To the best of our knowledge, only seven cases of intracerebral subependymoma have been reported. We report a rare case of intracerebral subependymoma in a child. An 11-year-old girl with generalized tonic-clonic seizures visited the emergency room and had an intraparenchymal tumor on the left frontal lobe on magnetic resonance imaging (MRI). Craniotomy with gross total removal was performed without any perioperative morbidities. The tumor was finally histopathologically diagnosed as a subependymoma.

Microsurgical Resection of the IV Ventricle Subependymoma: 2-Dimensional Operative Video

In this video, we demonstrate microsurgical resection of IV ventricle subependymoma. To the best of our knowledge, this is the first video case report of a microsurgical resection of subependymoma of the IV ventricle in the peer-reviewed English literature.

Subependymomas are benign central nervous system tumors, typically arising in ventricular spaces, mostly in the IV and lateral ventricles.^1-3 They are isointense on T1 and hyperintense on T2-weighted magnetic resonance imaging (MRI) with minimal or no enhancement.⁴ Microsurgery remains the mainstay treatment. Complete tumor resection is possible and curative with excellent prognosis.^1,5-7 Although the clinical course appears benign, the inability to diagnose them radiographically with certainty and the possibility of an alternative malignant lesion support a low threshold for early and safe resection.⁸

A 39-yr-old man presented with severe headache and balance problems. Pre- and postcontrast neuroaxis MRI revealed a centrally located IV ventricle lesion without hydrocephalus. The aim of the surgery was complete tumor resection. Surgery was performed in the prone position by the senior author (KIA) with intraoperative neurophysiology monitoring. A small suboccipital craniotomy and C1 posterior arch removal was done. After opening the dura and arachnoid membrane, the tumor was identified and meticulously dissected from the adjacent posterior inferior cerebellar artery and the floor of the fourth ventricle and from brain stem white matter at the tumor-neural tissue interface to avoid brainstem interference. Histological analysis revealed subependymoma (World Health Organization Grade I). Postoperative pre- and postcontrast MRI revealed complete resection. Headache and balance problems completely resolved; the patient was neurologically intact.

The patient provided written consent and permission to publish his image.

Intramedullary Masses of the Spinal Cord: Radiologic-Pathologic Correlation

Spinal cord tumors are a challenge for patients and neurosurgeons because of the high risk of neurologic deficits from the disease process and surgical interventions. Spinal cord tumors are uncommon, and approximately 2%-3% of primary intra-axial tumors of the central nervous system occur in the spinal cord. Primary intra-axial tumors are usually derived from neuroepithelial tissue, especially glial cells. This often leads to a classic intramedullary mass differential diagnosis of ependymoma or astrocytoma, which together constitute up to 70% of spinal cord tumors. For example, ependymomas occur predominantly in adults, and astrocytomas (specifically pilocytic astrocytomas) occur predominantly in children. While that is an excellent starting point, in order to refine the differential diagnosis, the authors review the radiologic-pathologic features of specific neoplastic categories and entities recognized by the World Health Organization (WHO) in the 2016 WHO Classification of Tumours of the Central Nervous System and a few additional congenital-developmental entities. Radiologists can add value by providing a reasonable preoperative differential diagnosis for the patient and neurosurgeon, in many cases by favoring the most common conditions, and in other cases by identifying radiologic features that may point toward a less common entity. Some of the less common entities include intramedullary myxopapillary ependymoma, spinal subependymoma, and spinal hemangioblastoma. Whenever possible, the characteristic imaging features and locations of these tumors are explained or traced back to the underlying cell of origin and findings seen at histopathologic examination.See discussion on this article by Buch.

Mutation Status and Epithelial Differentiation Stratify Recurrence Risk in Chordoid Meningioma-A Multicenter Study with High Prognostic Relevance

Chordoid meningioma is a rare WHO grade II histologic variant. Its molecular alterations or their impact on patient risk stratification have not been fully explored. We performed a multicenter, clinical, histological, and genomic analysis of chordoid meningiomas from 30 patients (34 tumors), representing the largest integrated study to date. By NHERF1 microlumen immunohistochemical detection, three epithelial differentiation (ED) groups emerged: #1/fibroblastic-like, #2/epithelial-poorly-differentiated and #3/epithelial-well-differentiated. These ED groups correlated with tumor location and genetic profiling, with NF2 and chromatin remodeling gene mutations clustering in ED group #2, and TRAF7 mutations segregating in ED group #3. Mutations in LRP1B were found in the largest number of cases (36%) across ED groups #2 and #3. Pathogenic ATM and VHL germline mutations occurred in ED group #3 patients, conferring an aggressive or benign course, respectively. The recurrence rate significantly correlated with mutations in NF2, as single gene, and with mutations in chromatin remodeling and DNA damage response genes, as groups. The recurrence rate was very high in ED group #2, moderate in ED group #3, and absent in ED group #1. This study proposes guidelines for tumor recurrence risk stratification and practical considerations for patient management.

Pediatric ependymoma: GNAO1, ASAH1, IMMT and IPO7 protein expression and 5-year prognosis correlation

OBJECTIVE

The aim of this work was to evaluate a pediatric ependymoma protein expression that may be useful as a molecular biomarker candidate for prognosis, correlated with clinical features such as age, gender, histopathological grade, ependymal tumor recurrence and patient survival.

PATIENTS AND METHODS

Immunohistochemistry assays were performed for GNAO1, ASAH1, IMMT, IPO7, Cyclin D1, P53 and Ki-67 proteins. Kaplan-Meier and Cox analysis were performed for age, gender, histopathological grade, relapse and survival correlation.

RESULTS

We found that three proteins correlate with histopathological grade and relapse; two proteins correlate with survival; one protein does not correlate with any clinical feature.

CONCLUSION

Our results suggest that, out of the proteins analyzed, five may be considered suitable prognostic biomarkers and one may be considered a predictive biomarker for response to treatment of pediatric ependymoma.

Spinal subependymoma surgery: do no harm. Little may be more!

OBJECTIVE

 Outline the reported diagnostic and operative findings, and evaluate the surgical treatment outcome to clarify the best available recommendations.

METHODS

 Ovid Medline, Embase and PubMed central databases were searched from inception until January 2019 using the terms (subependymoma and (spinal or cervical or thoracic)). The articles were reviewed for reported spinal subependymoma cases perioperative management and treatment outcomes.

RESULTS

 A total of 49 papers provided data on 105 cases. 47 cases were reported in the last 5 years. The reported cases were two medullary-cervical, 35 cervical, 32 cervicothoracic, 21 thoracic, 12 thoracolumbar and three lumbar. Spinal subependymomas typically arise from within the central spinal canal, giving the appearance of an intramedullary mass, usually eccentric to one side. Symptoms at presentation ranged between 1 month to 17 years, (mean 3.5 years, median 2 years) and were over 3 years in 36, and over 8 years in 12 cases. Sensory symptoms are the most frequent 75(80%), followed by weakness in 60(64%), pain in 45(48%) and sphincter disturbance in 24(25%). Postoperative neurological function was reported in 78 cases, and worsening was reported in 40 cases (51%), of which, 29 (72%) had complete resection, 6 (15%) had subtotal resection and 5 (12%) had partial resection. Neurological status remained the same in 24 (30%) and improved in 14 (18%).

CONCLUSION

 The reviewed cases report a rate of 65% total resection of which 57% had worsened function after surgery. There were no reports of malignant transformation; therefore, long-term survival is expected, and surgical caution should be exercised where there is minimal symptom progression.

Unusual Exophytic Appearance of Spinal Cord Subependymoma

BACKGROUND

Subependymomas are rare in the spinal cord. They are typically expansile, intramedullary spinal cord masses, eccentrically located with minimal gadolinium enhancement.

CASE DESCRIPTION

We present a case of subependymoma originating from the cervical cord with an unusual exophytic appearance. Hallmarks of subependymoma and treatment are reviewed.

CONCLUSIONS

This is the first case, to our knowledge, where imaging revealed a mass appearing to be completely extramedullary with a primary exophytic component. Therefore, subependymomas should remain on the differential for masses in the spinal cord that appear extramedullary and exophytic.

Subependymoma involving multiple spinal cord levels: A clinicopathological case series with chromosomal microarray analysis

Subependymomas of the spinal cord are rare, do not often involve multiple levels, and very rarely recur. Here, we present a series of spinal cord subependymomas with a detailed description of the clinical, radiological and pathological features, and characterization by chromosomal microarray analysis. Briefly, the four patients included two men and two women, between the ages of 22 and 48 years. The most common presenting symptoms were neck and arm pain with upper extremity weakness. By imaging, the tumors were found to involve multiple spinal levels, including cervical/ cervico-thoracic (three patients) and thoracic (one patient), were all eccentric, and had minimal to no post-contrast enhancement. Two patients underwent gross total resection, one had a sub-total resection, and one underwent biopsy alone with a decompressive laminectomy. Follow up ranged from 6 months to 22 years. One patient (case 4) had recurrence 15 years following gross total resection and chromosomal microarray analysis revealed deletions on the long arm of chromosome 6. Our limited series suggests that spinal cord subependymomas can rarely recur, even following gross total resection, suggesting a possible role for long-term surveillance for these rare tumors.

The role of inflammation in subventricular zone cancer

The adult subventricular zone (SVZ) stem cell niche has proven vital for discovering neurodevelopmental mechanisms and holds great potential in medicine for neurodegenerative diseases. Yet the SVZ holds a dark side - it can become tumorigenic. Glioblastomas can arise from the SVZ via cancer stem cells (CSCs). Glioblastoma and other brain cancers often have dismal prognoses since they are resistant to treatment. In this review we argue that the SVZ is susceptible to cancer because it contains stem cells, migratory progenitors and unusual inflammation. Theoretically, SVZ stem cells can convert to CSCs more readily than can postmitotic neural cells. Additionally, the robust long-distance migration of SVZ progenitors can be subverted upon tumorigenesis to an infiltrative phenotype. There is evidence that the SVZ, even in health, exhibits chronic low-grade cellular and molecular inflammation. Its inflammatory response to brain injuries and disease differs from that of other brain regions. We hypothesize that the SVZ inflammatory environment can predispose cells to novel mutations and exacerbate cancer phenotypes. This can be studied in animal models in which human mutations related to cancer are knocked into the SVZ to induce tumorigenesis and the CSC immune interactions that precede full-blown cancer. Importantly inflammation can be pharmacologically modulated providing an avenue to brain cancer management and treatment. The SVZ is accessible by virtue of its location surrounding the lateral ventricles and CSCs in the SVZ can be targeted with a variety of pharmacotherapies. Thus, the SVZ can yield aggressive tumors but can be targeted via several strategies.