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)/ß-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 ß-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.

Intramedullary Subependymoma Of Lower Thoracic Cord.

Spinal subependymoma (SSE) is a rare intramedullary, benign tumour. Surgical excision isthe preferred approach. However, the interwoven pattern of neural tissue within the tumour dictates the extent of resection. Where gross total resection is linked with possible neurological deficits, subtotal resection or close observation may support better functional outcomes. The evidence for the management of SSE is based mostly on case reports. Herein, we review the existing literature regarding treatment options and clinical outcomes of spinal subependymoma.

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.

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.

Subependymoma of the Conus Medullaris with Cystic Formation: Case Report and a Literature Review.

BACKGROUND: Subependymoma in the spinal cord is very rare and usually occurs in the cervical cord. We report an exceptional case of subependymoma that occurred at the conus medullaris with cystic formation. This article reviews the literature on subependymoma in the conus medullaris; discusses its clinical manifestations, imaging findings, and differential diagnoses; and offers an opinion about the cystic formation of the subependymoma. CASE DESCRIPTION: A 69-year-old woman experienced progressive limb weakness with a somatosensory abnormality for 3 months. Preoperative magnetic resonance imaging showed a cystic intramedullary lesion at the conus medullaris with a well-defined margin. A preliminary diagnosis of epidermoid cyst was made based on the imaging findings. During the operation, cystic formation of the tumor was found, and the tumor was completely removed. Pathology showed an uneven proliferation of glial cells, consistent with subependymal morphology, and the tumor was confirmed as subependymoma. CONCLUSIONS: We present an extremely rare case of cystic formation in subependymoma at the conus medullaris. Subependymoma should be included in the differential diagnosis of intramedullary cystic lesions. The breakdown of the blood-brain barrier and excessive extravasation may be potential mechanisms of cystic formation.

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.

Detection of H3K27M mutation in cases of brain stem subependymoma.

Subependymomas are rare, slow-growing, grade I glial tumors of the central nervous system. Recently, diffuse midline gliomas with mutations in the H3.1 or H3.3 genes at the position of amino acid 27, resulting in the replacement of lysine by methionine (K27M), were defined as the new grade IV entity. As H3K27M mutations have been reported in midline gliomas, gangliogliomas, and pilocytic astrocytomas, whether they occur in midline subependymomas has been unclear. We determined whether any such mutations can be found in them and analyzed the prognostic relevance of any such mutations in subependymomas. Four subependymomas, all in the brain stem, harbored H3K27M mutations. No such mutation was found in any of the subependymomas from other locations. The mutations were identified by immunohistochemical stains and confirmed with Sanger sequencing. The median follow-up of the patients with the mutations in their tumors was 3.2 years, and 3 are still alive, having received no adjuvant therapy. We demonstrate that H3K27M mutation can occur in brainstem subependymomas; despite the presence of H3K27M mutation, these cases should not be diagnosed or treated as grade IV tumors because they showed a better outcome than the outcome of diffuse midline H3K27M mutant glioma. Our conclusion is not only that brainstem subependymomas can have H3K27M mutations but that they do not carry the rapidly lethal prognosis with which these mutations are usually associated because of their discovery in diffuse intrinsic pontine gliomas.

A symptomatic large subependymoma with neuroradiological features mimicking a high-grade glioma: A case report.

A subependymoma is a benign primary brain tumor classified as a World Health Organization grade I tumor; it is asymptomatic in most cases. We present the case of a 66-year-old Japanese man with a complaint of recurrent vomiting that led to the discovery of a large mass with hemorrhage, peritumoral edema, and a midline shift in the posterior horn of the right lateral ventricle. The patient was pathologically diagnosed with subependymoma after undergoing total tumor resection; a year after the surgery, he was free from tumor recurrence. Although symptomatic subependymomas are rare, they tend to show hemorrhage with peritumoral edema on neuroradiological tests and tend to be confused with high-grade brain tumors. In the present case, we highlight the importance of the appropriate diagnosis for subependymomas showing neuroradiological features that mimic high-grade gliomas. This diagnosis will help in providing suitable treatment for subependymomas.

Subependymomas - Characteristics of a "Leave me Alone" Lesion. / Subependymome ­ Charakteristika einer "leave me alone"-Läsion.

PURPOSE: Intracranial subependymomas are rare, mostly asymptomatic tumours, which are often found incidentally and therefore did not receive much attention in previous literature. By being classified as benign grade I in the WHO classification of tumours of the central nervous system, they are given a special status compared to the other ependymal tumours. Tumor recurrences are a rarity, spinal "drop metastases" do not occur. While etiological, pathological and therapeutic characteristics have been subject of several publications over the last few decades and have meanwhile been well studied, the imaging characteristics are much less well received. MATERIAL AND METHOD: Retrospective analysis of our relatively large group of 33 patients with subependymoma, including 4 patients with a mixture of subependymomas with ependymal cell fractions in terms of imaging and clinical aspects and with reference to a current literature review. RESULTS: Subependymomas have typical image morphologic characteristics that differentiate them from tumors of other entities, however, the rare subgroup of histopathological mixtures of subependymomas with ependymal cell fractions has no distinctly different imaging properties. CONCLUSIONS: Knowing the imaging characteristics of subpendymoma and their differential diagnoses is of particular importance in order to be able to decide between the necessity of follow-up controls, an early invasive diagnosis or, depending on the entity, tumor resection. KEY POINTS: · Subependymomas have typical imaging characteristics that are clearly distinguishable from other entities.. · Increased incidence in middle/ older aged men, most frequent localization: 4th ventricle.. · Symptomatic subependymomas, often located in lateral ventricles, are usually characterized by hydrocephalus.. · Radiological identification of mixed subependymoma with ependymal cell fractions is not possible.. · Image based differentiation from other entities is important for the procedure.. CITATION FORMAT: · Kammerer S, Mueller-Eschner M, Lauer A et al. Subependymomas - Characteristics of a "Leave me Alone" Lesion. Fortschr Röntgenstr 2018; 190: 955 - 966.

Intratumoral Hemorrhage as an Unusual Manifestation of Intracranial Subependymoma.

BACKGROUND: Subependymoma is rare, and little is known about subependymoma with intratumoral hemorrhage. METHODS: A retrospective study of subependymoma was performed. Among 61 subependymomas, 4 cases of intratumoral hemorrhage were collected. All 4 cases were pathologically confirmed to be subependymoma and showed a benign character. RESULTS: After complete subependymoma resection, the 4 patients achieved favorable outcomes. Pathology showed that dilated thin-walled vessels and/or hyalinosis of the vessel walls existed in all 4 cases. CONCLUSIONS: The present series showed that subependymomas with hemorrhage and benign pathology are rare and that surgical treatment results in good prognosis. This series supports the hypothesis that the pathology of vascular degeneration may contribute to subependymoma hemorrhage.

Squash cytology findings of subependymomas: A report of three cases and differential diagnosis.

Subependymomas are slowly growing glial tumors, corresponding to WHO grade I. Few descriptions of the cytologic features of this neoplasm are available. This study describes the cytologic features of three subependymomas, as well as their differential diagnosis based on cytology. Three men, aged 52, 56, and 63 years, presented with headache. Magnetic resonance imaging revealed a nodular intraventricular mass in all three patients. Intraoperative squash cytology specimens from the three intraventricular tumors showed nodular clusters with microcystic changes. Nuclei were round to oval in shape, but showed no evidence of severe nuclear atypia or mitoses. Histological examination showed features of subependymoma. Squash cytology findings, including nodular clusters, mild cellular atypia, microcystic changes, and mucoid material, are useful in the rapid intraoperative diagnosis of subependymoma.

Bilateral lateral ventricular subependymoma with extensive multiplicity presenting with hemorrhage.

This 48-year-old-man who had undergone right thyroid lobectomy for undifferentiated thyroid carcinoma nine years earlier developed generalized seizures. His cerebrospinal fluid was xanthochromic with elevation of total protein. Computed tomography (CT) showed mixed-density bilateral ventricular masses. Magnetic resonance imaging (MRI) revealed multiple nodules in both lateral ventricles; they were heterogeneously enhanced by gadolinium. Diffuse hyperintensity in the right medial temporal lobe and bilateral subependymal area was noted on fluid-attenuated inversion recovery images. Susceptibility-weighted imaging showed low intensity in the masses and cerebellar sulci suggesting hemorrhage and hemosiderin deposition. The preoperative diagnosis was disseminated malignant tumor with recurring hemorrhage. Histological examination of biopsy specimens showed clusters of cells with small uniform nuclei embedded in a dense fibrillary matrix of glial cells and microcystic degeneration. Pseudo-rosettes indicating ependymoma were absent. Microhemorrhages and hemosiderin deposits were noted. Immunohistochemically, the background fibrillary matrix and neoplastic cells were positive for glial fibrillary acidic protein. Mutated isocitrate dehydrogenase-1 was negative. The MIB-1 index was 1.5%. The tumor was pathologically diagnosed as subependymoma containing microhemorrhages and hemosiderin deposits. The extensive multiplicity and hemorrhage encountered in this case have rarely been reported in patients with subependymoma.

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

OBJECTIVE: Subependymomas are infrequent, low-grade gliomas associated with the ventricular system and the spinal cord. Little is known about the origin and natural history of these slow-growing lesions. METHODS: We identified all patients with pathologically proven subependymomas presenting to our institution between 1998 and 2016. We retrospectively reviewed clinical, radiographic, histologic, and surgical outcomes data in all patients who underwent surgical resection. Immunohistochemical analyses for cell lineage markers were performed. RESULTS: A total of 31 patients with pathologically proven subependymomas were identified. Of these, 7 asymptomatic lesions were discovered at autopsy and 24 symptomatic cases were treated surgically. There were 15 (48%) lateral ventricle tumors, 11 (35%) fourth ventricular tumors, and 5 (17%) spinal tumors. Symptomatic intracranial lesions most commonly presented with headaches and balance and gait abnormalities. Subependymomas had no distinguishing radiographic features that provided definitive preoperative diagnosis. At last follow-up, no patient treated surgically experienced recurrence. Immunohistochemical analyses demonstrated a diffusely GFAP-positive glial neoplasm with mixed populations of cells that were variably positive for Olig2, NHERF1, Sox2, and CD44. The Ki67 proliferation index was generally low (<1% in many of the tumors). CONCLUSIONS: Subependymomas demonstrate mixed populations of cells expressing glial lineage markers as well as putative stem cell markers, suggesting these tumors may arise from multipotent glial progenitors that reside in the subventricular zone. Definitive diagnosis requires surgical sampling. Although the clinical course of subependymomas appears benign, the inability to radiographically diagnose these lesions, and the possibility of an alternative malignant lesion support a low threshold for early and safe maximal resection.

Tuberous sclerosis complex: Imaging characteristics in 11 cases and review of the literature.

Tuberous sclerosis complex (TSC) is an uncommon multiorgan disorder that may present many and different manifestations on imaging. Radiology plays an important role in diagnosis and management, and can substantially improve the clinical outcome of TSC. Therefore, a comprehensive understanding of this disease is essential for the radiologist. The manifestations of TSC on computer tomography (CT) and magnetic resonance (MR) images were analyzed. Eleven patients with a clinical diagnosis of TSC were retrospectively reviewed. Central nervous system lesions included subependymal nodules (SENs) (11/11), subependymal giant cell astrocytomas (SEGAs) (2/11), cortical and subcortical tuber lesions (5/11), and white matter lesions (4/11). Of the 6 patients with abdominal scans, there were 6 cases of renal angiomyolipomas (AMLs), and one case of hepatic AMLs. Of the 4 patients undergoing chest CT, lung lymhangioleiomyomatosis (LAM) (2/4), and multiple small sclerotic bone lesions (2/4) were observed. Different modalities show different sensitivity to the lesion. Analysis of images should be integrated with patients' history in order to diagnose TSC.

Biology and management of ependymomas.

Ependymomas are rare primary tumors of the central nervous system in children and adults that comprise histologically similar but genetically distinct subgroups. The tumor biology is typically more associated with the site of origin rather than being age-specific. Genetically distinct subgroups have been identified by genomic studies based on locations in classic grade II and III ependymomas. They are supratentorial ependymomas with C11orf95-RELA fusion or YAP1 fusion, infratentorial ependymomas with or without a hypermethylated phenotype (CIMP), and spinal cord ependymomas. Myxopapillary ependymomas and subependymomas have different biology than ependymomas with typical WHO grade II or III histology. Surgery and radiotherapy are the mainstays of treatment, while the role of chemotherapy has not yet been established. An in-depth understanding of tumor biology, developing reliable animal models that accurately reflect tumor molecule features, and high throughput drug screening are essential for developing new therapies. Collaborative efforts between scientists, physicians, and advocacy groups will enhance the translation of laboratory findings into clinical trials. Improvements in disease control underscore the need to incorporate assessment and management of patients' symptoms to ensure that treatment advances translate into improvement in quality of life.

Neuroradiological features of cervical and cervicothoracic intraspinal subependymomas: a study of five cases.

AIM: To characterize the magnetic resonance imaging (MRI) findings in a series of five patients with cervical and cervicothoracic intraspinal subependymomas and to increase awareness of this neoplasm. MATERIALS AND METHODS: The clinical and radiological profiles of five patients who were diagnosed with subependymoma based on histopathological findings were retrospectively studied and compared with previously reported cases. All patients underwent enhanced MRI. RESULTS: One patient presented with a subependymoma of the cervical spine, one patient harboured a thoracic spinal subependymoma, and the other patients presented with cervicothoracic subependymomas. All lesions were hypointense on T1-weighted images and hyperintense on T2-weighted images. One lesion grew centrally, whereas the others demonstrated eccentricity. Partially faint enhancement was noted in four cases, and one case demonstrated multinodular moderate enhancement. CONCLUSION: Cervical and cervicothoracic intraspinal subependymomas can be distinguished on MRI images. Specifically, a faintly enhanced or non-enhanced heterogeneous intramedullary lesion that exhibits a slowly deteriorating clinical course may be indicative of a subependymoma. In such cases, resection is expected to yield favourable outcomes.

Findings from frozen sections of spinal subependymomas: Is it possible to differentiate this diagnosis from other common spinal tumors?

Subependymomas are slow-growing, benign neoplasms that are rarely found in the spinal cord. Because of the differences in the treatment plans, it might be very helpful for neurosurgeons to intraoperatively establish a diagnosis of spinal subependymoma, differentiated from other spinal intramedullary tumors. In this study, we analyzed frozen sections of spinal subependymomas to identify potential histological clues of spinal subependymomas to differentiate them from tumors that mimic spinal subependymoma. We reviewed the frozen sections and the corresponding permanent slides for 7 cases of spinal subependymoma. The spinal subependymomas showed several characteristic patterns, including, most importantly, an eccentric or both central and eccentric location in the axial plane. Histologically, they showed a (1) well-demarcated and multinodular mass with (2) low or moderate cellularity, (3) a microlobular pattern, and (4) small clusters of neoplastic cells. These features appear to be very specific to spinal subependymomas and could help differentiate them from ependymomas or astrocytomas. Although we might not be able to provide an exact diagnosis of all spinal subependymomas using these histological features, we hope that they help neuropathologists and neurosurgeons to adequately diagnose and treat spinal subependymomas.