Is This Truly A "Leave-Me-Alone" Lesion? An Unusual Case of Multiple Ring-shaped Lateral Ventricular Nodules

BACKGROUND

Ring-shaped lateral ventricular nodules (RSLVNs) are commonly considered as benign asymptomatic lesions, which are sporadically detected as incidental findings on routine brain magnetic resonance imaging scans. Despite their not irrelevant frequency, the exact biological nature of these lesions remains largely unknown due to the lack of histopathologic studies. Here we present the clinical, neuroradiologic, and histopathologic findings of an unusual case of symptomatic multiple RSLVNs.

CASE DESCRIPTION

A 44-year-old otherwise healthy man presented with a recent history of headache and retching. Neuroradiologic imaging revealed the presence of multiple RSLVNs, the largest of which, located in the cella media of the right lateral ventricle, exerted a mild to moderate mass effect on adjacent brain parenchyma. This latter nodule was successfully removed, with complete resolution of the symptoms. Histopathology revealed glial differentiation, and the specimen was diagnosed as subependymoma.

CONCLUSIONS

This report provides novel evidence characterizing RSLVNs as possible variants of subependymoma with a peculiar imaging appearance, also suggesting that, like subependymomas, they may occasionally grow large enough to cause mass effect-related symptoms, thus requiring neurosurgical intervention.

Symptomatic subependymomas of the ventricles. Review of twenty consecutive cases

BACKGROUND AND PURPOSE

Intraventricular subependymomas are rare benign tumors, which are often misdiagnosed as ependymomas. To review the clinicopathological features of subependymomas. PATIENT SELECTION AND METHODS: Retrospective clinical analysis of intraventricular subependymomas and systematic review of histological slides operated on at our center between 1985 and 2005.

RESULTS

Twenty subependymomas presented at the median age of 50 years (range 19-77). Two (10%) were found in the third, three (15%) in the forth, and 15 in the lateral ventricles. There was male preponderance (12 vs. 8). Ataxia (n=13) and papilledema (n=7) were the most common clinical presentations. Fifteen patients underwent gross total resection, and five had subtotal resection. None of the cases showed mitotic figures, vascular endothelial proliferation or necrosis. Cell proliferation marker MIB-1 activity (percentage of positive staining tumor cells) ranged from 0 to 1.4% (mean 0.3). Two cases were treated with preoperative radiation therapy (50 Gy) before the CT era, three other patients received postoperative radiation therapy for tumors originally diagnosed histologically as low grade ependymomas. Three patients (15%) died of surgical complication between one and three months postoperatively, and three patients died of unrelated causes in eight, 26 and 110 months. Fifteen patients were alive without evidence of tumor recurrence at a median follow-up time of 10 years.

CONCLUSION

Subependymomas are low-grade lesions and patients do well without adjuvant radiotherapy. Small samples from more cellular areas may be confused with low grade ependymomas, and unnecessary radiotherapy may follow. Recurrences, rapid growth rates should warrant histological review, as hypocellular areas of ependymomas may also be a source of confusion.

A case of septum pellucidum subependymoma with a subtle imaging appearance simulating a cavum septum pellucidum

Subependymoma is a rare benign slowly growing tumor which usually appears as a well-defined lobulated entirely intraventricular mass, in the fourth or lateral ventricles. We report a case of subependymoma involving the septum pellucidum in a 28 year old female demonstrating a subtle and unusual radiological appearance. It showed very low attenuation on computed tomography, with very high signal on T2- and low signal on T1 weighted magnetic resonance images, merging with the ventricular wall, without definite focal mass. This appearance made the tumor difficult to differentiate from the cerebrospinal fluid and simulating a cavum septum pellucidum. The patient was treated by craniotomy and gross total resection of the mass.

[Subependymoma of the lateral ventricle. A case report]

INTRODUCTION. Intracranial subependymomas are rare, slow-growing, noninvasive, benign tumors. They are most often located in the fourth ventricle. Most of these tumors are discovered incidentally during autopsy. Routine medical checkups using neuroimaging techniques have increased their diagnosis. Subependymomas may present with symptoms related to cerebrospinal fluid obstruction or mass effect. CASE REPORT. A 52-year-old man presented with severe headache and mental deterioration with memory disturbances and bradypsychia. Computed tomography and magnetic resonance imaging revealed a mass in the right lateral ventricle causing obstructive hydrocephalus. The tumour was totally removed through a right frontal transcortical approach. Histological examination showed a typical subependymoma. A complete neurological recovery was achieved after surgery. CONCLUSIONS. Subependymomas are rare low-grade glial neoplasm that commonly arise in the ventricular system. They have a low-proliferative potential but in these locations they can cause symptomatic hydrocephalus. Surgical removal of the mass and the restoration of the normal cerebrospinal fluid pathways constitute the optimal management strategy.

Unusual appearance and presentation of supratentorial subependymoma in an adult patient

We report a case of a large, heterogeneously enhancing, pathologically proven, supratentorial subependymoma in a 31-year-old male patient presenting with headache, nausea and vomiting as well as gait disturbances. Although most supratentorial subependymomas have distinctive MR features, our case demonstrated imaging findings that made it indistinguishable from other more aggressive malignant supratentorial intraventricular lesions. It is of paramount importance to consider supratentorial subependymomas in the differential diagnosis of supratentorial lesions, even if their radiological features were atypical.

Subependymoma at the foramen of Monro presenting with intermittent hydrocephalus: case report and review of the literature

Subependymomas are benign neoplasms, accounting for 0.5 % of all central nervous system tumors. These tumors are frequently asymptomatic, often discovered incidentally at autopsy. However, patients may be symptomatic with the symptoms depending on location of the tumor. Since subependymomas typically arise from the ventricular wall, obstruction of cerebrospinal fluid is a major cause of onset symptoms. We present a rare case report of a subependymoma at the foramen of Monro presenting with intermittent hydrocephalus. The patient's tumor was asymptomatic for many years. Imaging findings included asymmetry of the lateral ventricles. The patient developed sudden onset of headache and altered mental status followed by complete resolution, likely due to intermittent hydrocephalus. She developed two more such episodes necessitating an emergent external ventricular drain placement followed by surgical resection. Our report illustrates a case of intermittent hydrocephalus due to a sessile subependymoma. Even though our patient presented with a histologically benign ventricular tumor, she demonstrated rapidly worsening symptoms that culminated in herniation. By presenting our case report, we hope to draw attention to this rare but potentially life-threatening presentation of subependymoma. Once diagnosed, we recommend early tumor removal and restoration of normal cerebrospinal fluid (CSF) pathways for these intraventricular tumors.

Subependymoma of the spine

Subependymoma is a rare benign CNS tumor (WHO grade I). The common sites of origin for this type of tumor are the lateral and the fourth ventricles. A spinal intramedullary location is rare. Radiological features of intramedullary subependymoma can mimic more common and more aggressive tumor types. We report a case of a 61-year-old male who presented with a 3-year history of low back pain, associated with right lower limb progressive weakness and sensory numbness. An MRI of the lumbar spine revealed an intradural intramedullary lesion extending from the level of T10-L1. Clinical presentation, radiological, and pathological studies of this case of subependymoma are presented. The incidence of spinal subependymoma was also discussed in light of a literature review.

Subependymomas: An analysis of Clinical and Imaging Features

OBJECTIVE:

Subependymomas are slow-growing, benign tumors usually found incidentally in the fourth ventricle at autopsy. They are typically associated with the ventricular system and become apparent clinically only when symptoms of hydrocephalus or mass effect develop. We review clinical, histological, and contemporary radiographic presentations of 16 subependymomas, including 2 intraparenchymal tumors.

METHODS:

We retrospectively evaluated eight patients with pathologically proven subependymomas. Initial magnetic resonance imaging and magnetic resonance spectroscopy were reviewed when available. Imaging was also available on eight outside subependymoma cases reviewed by our radiology department.

RESULTS:

Twelve of these subependymomas were intraventricular, one was in the posterior fossa, two were intraparenchymal, and one was an intramedullary spinal cord tumor. These lesions were hypo- to hyperintense on T1- and T2-weighted magnetic resonance imaging, with minimal to moderate enhancement. Initial complaints included headache, seizures, tingling sensations, and weakness. Among our eight patients who underwent gross total resection with no adjuvant therapy, no recurrences have been noted on follow-up magnetic resonance imaging.

CONCLUSION:

Subependymomas are rare, representing only 0.51% of all central nervous system tumors operated on during an 8-year period at the University of Utah. Clinical symptoms were associated with tumor location: intracranial masses caused headaches, seizures, and neurological complaints, and spinal cord locations resulted in neurological deficit. The authors review the clinical presentation, management, and contemporary radiographic appearance of this rare tumor.

Rapid expansion of a previously asymptomatic subependymoma

✓ This 39-year-old man presented with a 6-month history of occipital headaches. Magnetic resonance imaging revealed an irregularly shaped fourth ventricle mass. One month after his initial presentation, he was admitted to the hospital with significant tumor expansion and clinical deterioration. A posterior fossa craniectomy was performed and the mass was resected. Histopathological analysis of this tumor showed central necrosis with associated edema in an otherwise typical and benign-appearing subependymoma. To the authors' knowledge, this is the first reported case of rapid, nonhemorrhagic expansion associated with necrosis in a previously asymptomatic subependymoma.

Massive symptomatic subependymoma of the lateral ventricles: case report and review of the literature

Subependymomas are benign intraventricular tumors with an indolent growth pattern, which are usually asymptomatic, and most commonly occur in the fourth and lateral ventricles. When symptomatic, subependymomas often obstruct critical portions of the cerebrospinal fluid (CSF) pathway, causing hydrocephalus, and range from 3 cm to 5 cm in size. We report a case of an unusually massive subependymoma of the lateral ventricles treated with subtotal resection, ventriculoperitoneal shunt, and post-surgical radiation. The clinical course, radiographic and pathologic characteristics of this massive intraventricular subependymoma are discussed, as well as the differential diagnosis of lateral ventricular masses and a review of the literature concerning subependymomas.

201Tl-SPECT and 1H-MRS study of benign lateral ventricle tumors: differential diagnosis of subependymoma

The introduction of computed tomography (CT) and magnetic resonance (MR) imaging has resulted in the detection of increasing numbers of asymptomatic intraventricular tumors. Establishing the correct preoperative diagnosis is important to prevent unnecessary surgical intervention. Our study includes nine cases of benign lateral ventricle tumors including two cases of central neurocytoma, two of subependymal giant cell astrocytoma, two of pilocytic astrocytoma and three of subependymoma treated surgically between 1996 and 2003. MR imaging, proton MR spectroscopy ((1)H-MRS) and thallium-201 single photon emission computed tomography ((201)Tl-SPECT) were performed in all patients. All three types of tumor demonstrated heterogeneous enhancement on MR imaging with gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) and increased choline (Cho) peak and decreased N-acetyl aspartate (NAA) and creatine (Cre) peaks on (1)H-MRS. (201)Tl-SPECT showed high uptake of (201)Tl without wash out in all cases of central neurocytoma, subependymal giant cell astrocytoma and pilocytic astrocytoma, but no uptake in cases of subependymoma. Absence of (201)Tl uptake in contrast with enhancement on MR imaging and the (1)H-MRS features of modest elevation of the Cho/Cre ratio, reduction of the NAA peak and presence of lactate/lipid peaks are characteristic features of subependymomas and useful to establish a preoperative diagnosis.

Subependymoma in the third ventricle in a child

Subependymomas are rare, slow-growing, benign intraventricular tumors which occur commonly in the fourth or lateral ventricle. They usually occur in elderly men and often are asymptomatic and discovered incidentally. We report a case of a 6-year-old girl with a symptomatic subependymoma in the third ventricle with MR imaging.

Intramedullary subependymoma of the spinal cord: a case report and review of literature

A case of cervical spine intramedullary subependymoma in a 52-year-old female is reported. Also, the relevant literature on the 40 cases reported till date is reviewed. Magnetic resonance imaging, even with enhancement, does not show any distinctive features making pre-operative diagnosis often difficult. These tumours are eccentrically located within the spinal cord, thus enabling complete tumour removal in most cases. They are benign with low proliferative potential and hence no post-operative radiotherapy should be administered.

Ependymomas

Ependymomas are uncommon neoplasms of the central nervous system (CNS), and as a consequence, few randomized, clinical trials have been performed, thereby limiting treatment guidelines. A review of the literature would permit the following conclusions regarding treatment. The best management of newly diagnosed ependymoma entails a complete resection corroborated by postoperative contrast-enhanced magnetic resonance imaging (MRI). If an incomplete resection is documented, a second attempt at gross total resection should be considered, given the prognostic significance of complete resection. Small volume residual disease is best managed with involved-field radiotherapy unless postoperative staging (cerebrospinal fluid cytology, neuraxis MRI) documents metastatic disease, which is best managed by craniospinal irradiation. The role of chemotherapy is uncertain and in general would be reserved for patients having previously failed surgery and radiotherapy. Disease-free survival following recurrence is unusual (<15% at 5 years) and suggests intensification of initial adjuvant treatment may best prevent relapse.

Intramedullary subependymoma occupying the right half of the thoracic spinal cord--case report

A 37-year-old female presented with a rare spinal subependymoma manifesting as progressive weakness of her right lower extremity over an 8-month period. She had a 10-year history of back pain and urinary disturbance. Magnetic resonance imaging showed diffuse enlargement of the spinal cord from T-2 to T-7 on the T1-weighted images. The enlarged spinal cord was divided into two compartments by a vertical septum-like structure on the T2-weighted images. The tumor occupied the right half of the thoracic spinal cord, and was totally removed through a laminectomy from T-2 to T-7. The histological diagnosis of the resected specimen was subependymoma. Subependymomas are slow-growing tumors usually found in the ventricular system. Spinal subependymomas are difficult to distinguish from other intramedullary spinal tumors based on neuroradiological findings. Subependymomas are surgically curable tumors, so if the tumor is well demarcated and a subependymoma is indicated, an attempt should be made to totally remove the tumor.

Tumours around the foramen of Monro: clinical and neuroimaging features and their differential diagnosis

The clinical and neuroimaging features of 20 patients with lateral ventricular tumours located around the foramen of Monro were reviewed retrospectively with special emphasis on the differential diagnoses. Histologic types were: eight neurocytomas, four subependymal giant cell astrocytomas (SGCAs), three subependymomas, two fibrillary astrocytomas, and one each of pilocytic astrocytoma, malignant astrocytoma and malignant teratoma. The mean age of the patients with neurocytoma was 29.6 years, with SGCA 13.3 years and with subependymoma 55.3 years. All tumours appeared nodular in shape, and on computed tomography (CT) neurocytomas were either isodense or highdense with the brain, while all subependymomas and SGCAs were lowdense. Calcification was observed in two SGCAs, and one neurocytoma. Five neurocytomas and all four SGCAs showed mild to moderate contrast enhancement, while all three subependymomas showed either no, or scarce, enhancement. Magnetic resonance imaging (MRI) studies were available in 10 patients, with the signal characteristics of four neurocytomas and three SGCAs being nonspecific, while two subependymomas were both hypointense on T1-weighted images and hyperintense on T2-weighted images. Thus important features for differential diagnosis included age of the patient and density on precontrast CT. In this series, either an extensive excision of the tumour or a partial removal, thus relieving the obstruction of the foramina of Monro, usually provided long term survival, with 18 patients surviving a mean of 10.8 years.

[Symptomatic subependymoma of the lateral ventricle in a young female]

We present a case of a symptomatic subependymoma (SE) in a young. The patient was a 20-year-old female who suffered from severe headache and vomiting. Precontrast CT scans revealed a large spotty-calcified isodensity mass lesion in the right anterior lateral ventricle, showing scarce contrast enhancement at the center of the mass and with marked hydrocephalus. MRI demonstrated the lesion as slightly hypo-intensity on T1-weighted image, hyper-intensity on T2-weighted image. On FLAIR imaging, the lesion indicated remarkable hyperintensity and was clearly distinguishable from surrounding brain parenchyma and the cerebrospinal fluid. After Gd-DTPA infusion central vein was revealed, but no tumor enhancement was seen. The tumor was totally extirpated through the transcortical approach. Histological diagnosis was SE, and high MIB-1 staining index (9.3%) was seen. FLAIR imaging is useful for the preoperative diagnosis and the postoperative assessment of SEs.

Distinct expression pattern of microtubule-associated protein-2 in human oligodendrogliomas and glial precursor cells

Microtubule-associated protein 2 (MAP2), a protein linked to the neuronal cytoskeleton in the mature central nervous system (CNS), has recently been identified in glial precursors indicating a potential role during glial development. In the present study, we systematically analyzed the expression of MAP2 in a series of 237 human neuroepithelial tumors including paraffin-embedded specimens and tumor tissue microarrays from oligodendrogliomas, mixed gliomas, astrocytomas, glioblastomas, ependymomas, as well as dysembryoplastic neuroepithelial tumors (DNT), and central neurocytomas. In addition, MAP2-immunoreactive precursor cells were studied in the developing human brain. Three monoclonal antibodies generated against MAP2A-B or MAP2A-D isoforms were used. Variable immunoreactivity for MAP2 could be observed in all gliomas with the exception of ependymomas. Oligodendrogliomas exhibited a consistently strong and distinct pattern of expression characterized by perinuclear cytoplasmic staining without significant process labeling. Tumor cells with immunoreactive bi- or multi-polar processes were mostly encountered in astroglial neoplasms, whereas the small cell component in neurocytomas and DNT was not labeled. These features render MAP2 immunoreactivity a helpful diagnostic tool for the distinction of oligodendrogliomas and other neuroepithelial neoplasms. RT-PCR, Western blot analysis, and in situ hybridization confirmed the expression of MAP2A-C (including the novel MAP2+ 13 transcript) in both oligodendrogliomas and astrocytomas. Double fluorescent laser scanning microscopy showed that GFAP and MAP2 labeled different tumor cell populations. In embryonic human brains, MAP2-immunoreactive glial precursor cells were identified within the subventricular or intermediate zones. These precursors exhibit morphology closely resembling the immunolabeled neoplastic cells observed in glial tumors. Our findings demonstrate MAP2 expression in astrocytic and oligodendroglial neoplasms. The distinct pattern of immunoreactivity in oligodendrogliomas may be useful as a diagnostic tool. Since MAP2 expression occurs transiently in migrating immature glial cells, our findings are in line with an assumed origin of diffuse gliomas from glial precursors.

Symptomatic child case of subependymoma in the fourth ventricle without hydrocephalus

We report a rare child case of symptomatic subependymoma in the fourth ventricle without hydrocephalus. The upper half of the tumor was demonstrated as a non-enhancing isodense mass with punctate calcification on CT, whereas the lower portion showed slightly irregular ring-like enhancement with a central hypodense area. The tumor was heterogeneously hyperintense on T2-weighted magnetic resonance (MR) images. When scanned with a T1-weighted sequence, the upper portion of the tumor was isointense to brain, but the lower portion was hypointense. However, using Gd-enhanced T1-weighted imaging, such as in postcontrast CT, the upper portion did not enhance, whereas the lower portion revealed similar ring-like enhancement, which was suggestive of necrosis. To further confirm the nature of the tumor, a diffusion-weighted imaging study with echo-planar technique was performed, and it indicated the solid nature of the tumor, which was confirmed histopathologically.

Subependymoma of the lateral ventricles

Four subependymomas of the lateral ventricle were reviewed with regard to clinical presentation, neuroimaging features, treatment, histopathological features, and long-term follow-up. There were two male and two female patients ranging in age from 27 to 60 years (mean 48.3 years). While two patients presented with symptoms and signs of raised intracranial pressure, two others were found incidentally during neuroimaging investigations to have intraventricular tumors. Neuroimaging characteristics of these tumors included no paraventricular extension, iso- or hypodensity with minimal enhancement on computerized tomography (CT), or iso- or hypointensity on T1-weighted and hyperintensity on T2-weighted magnetic resonance images (MRI). The usual finding on MRI was of no or scarce contrast enhancement, but one case showed heterogeneous enhancement. Three patients underwent total resection of the tumor and one underwent partial resection. No patients received postoperative radiation therapy. All patients have been doing well 4.8 to 15.4 years (mean 8.8 years), after surgery. Although there are no absolutely specific features to distinguish these tumors from other intraventricular tumors preoperatively, subependymoma should be kept in mind for differential diagnosis, as this tumor may safely be removed without sacrificing contiguous normal tissue and with good long-term results.

Hemangioblastomas and other uncommon intramedullary tumors

Astrocytoma and ependymoma make up 90% of intramedullary tumors between them. However, a host of less common tumors form the remaining 10%: these include hemangioblastomas, subependymomas, gangliogliomas and other neuronal variants, metastases from extraneural cancers, and a host of other lesions that typically occur intracranially but which present on rare occasions in the intramedullary location. Most neurosurgeons will encounter the unusual tumors of the spinal cord described in this review only a few times during their professional careers, but it is nevertheless important to recognize the distinct radiological and intraoperative features of those for which significant series of patients have been accumulated. Metastases and germinomas aside, the other neoplasms described here are relatively benign in their clinical and histological behavior, and can be meaningfully resected by careful microsurgical technique.

Intracranial subependymoma

Subependymomas most commonly appear as a mass in the fourth ventricle of adults; these tumors are rare but must be considered in the differential diagnosis of a lesion arising in this location. We report a case of a fourth ventricule subependymoma.

Subependymoma in the lateral ventricle incidentally detected by routine brain examination--case report

A 42-year-old male visited our hospital for a routine brain examination, which incidentally identified an intraventricular mass lesion (2.7 x 1.6 x 1.2 cm3). Magnetic resonance imaging showed the tumor was isointense on the T1-weighted image and hyperintense on the T2-weighted and proton images. The intraventricular tumor was totally extirpated through the interhemispheric ipsilateral transcallosal approach. The histological diagnosis was subependymoma. Neuroimaging cannot differentiate this benign neoplasm from other more aggressive tumors. Widespread use of the medical checkup system is expected to find a higher incidence of otherwise non-identified asymptomatic lesions. Surgical extirpation is one of the treatment options to establish the correct diagnosis and to prevent symptoms.

Lateral ventricle subependymomas. Case report taking into particular consideration the aspects of magnetic resonance and review of the literature

Subependymomas are rare neuroectodermic tumours. The authors report a case of a patient he had a subendymoma in the left lateral ventricle, with particular attention to the MR aspects on these lesions and review of the literature.

Resolution of subependymal cysts in neonatal holocarboxylase synthetase deficiency

Holocarboxylase synthetase deficiency is typically a biotin responsive disorder that presents with lactic acidosis, tachypnea, temperature instability, and shock in neonates (Briones et al.1989 and Fuchshuber et al. 1992). The primary defect in cases studied to date appears to be the decreased affinity of HCS for its substrate, biotin (Gompertz et al. 1971). Supplemental biotin can provide sufficient substrate to increase HCS enzymatic function and thereby permit biotinylation of the four carboxylase apoenzymes (Briones et al. 1989). We report an infant with HCS deficiency who presented with lactic acidosis, shock, and hypertonia. Subependymal cysts were identified on cranial ultrasound and subsequently confirmed by MRI. Six months following biotin supplementation, she is developmentally normal and MRI of the brain shows complete resolution of the cysts.

Symptomatic subependymomas of the lateral ventricles. Report of eight cases

Subependymomas are rare, slow-growing, benign intraventricular tumors, which often are asymptomatic and are discovered incidentally. The review of the literature shows more than 100 symptomatic cases, less than half located in the lateral ventricles. Here we report 8 cases of symptomatic subependymomas of the lateral ventricles, studied by CT and/or MR and treated by direct surgical approach. The suspicion of a subependymoma should arise when a patient older than 10-15 years with long clinical history presents an intraventricular tumor isodense on CT and isointense in T1 and hyperintense in T2 on MR, with scarce or discrete contrast enhancement. Surgical treatment is indicated in symptomatic subependymomas of the lateral ventricles and usually allows complete tumor removal. The prognosis is usually good, also without postoperative irradiation.

Tumors and approaches to the lateral ventricles. Introduction and overview

There are a variety of tumors that arise within the lateral ventricles and they present a unique surgical challenge. These lesions commonly are benign and because they frequently are slowly expanding and cause non-specific symptoms they can grow to a large size before they reach medical attention. This report presents an introduction to and an overview of the problems caused by lateral ventricular tumors and summarizes the author's experience in the evaluation and management of these lesions. The most consistent neurological problems associated with lateral ventricular tumors are cognitive impairments commonly associated with hydrocephalus. Consequently, effective management not only requires successful surgical therapy, but also returning the patient to normal neurological and cognitive function. Recognition of these problems and minimizing further injury are the best methods of providing for an optimal outcome.

Intramedullary subependymoma of the spinal cord

A consecutive series of six patients underwent operative resection of intramedullary spinal cord subependymomas between January 1981 and August 1993. Three men and three women between the ages of 26 and 66 years experienced symptoms for a mean of 50 months preceding diagnosis. The locations of the tumors were predominantly cervical or cervicothoracic, except in one patient. At operation, a complete extirpation was achieved in each patient. No patient received further adjunct therapy. There has been no tumor recurrence in any patient after a mean follow-up period of 39 months. Most of the intramedullary spinal cord tumors are either ependymomas or astrocytomas. Clinical histories, physical examinations, and radiographic investigations are not conclusive for absolute diagnosis of subependymomas; however, intraoperative gross observations have shown these well-demarcated tumors to be located eccentrically within the spinal cord. Pathological examinations demonstrate tumors with sparse cellularity, clustering of cells, and dense fibrillary stroma. Proliferation studies with the mouse monoclonal antibody MIB-1 reconfirm the slow growth potential of these benign tumors.

Intracranial subependymomas: CT and MR imaging features in 24 cases

OBJECTIVE

The intracranial subependymoma is a benign glioma that has been classically described as an asymptomatic fourth ventricular tumor found incidentally at autopsy in elderly men. The purpose of this study was to characterize the differences in CT and MR imaging appearances between subependymomas of the fourth and lateral ventricles, both of which were found in symptomatic patients.

MATERIALS AND METHODS

We retrospectively reviewed 24 pathologically proved cases of intracranial subependymomas in 17 male and seven female patients with a mean age of 48.1 years. All patients were symptomatic. CT and MR images were used to characterize the size, shape, and location of the subependymomas; the degree of hydrocephalus; tumor calcification; and the density, signal, and enhancement characteristics of the tumors.

RESULTS

Eighteen of 24 tumors were 3 cm or more in greatest dimension. Nineteen were lobulated, and hydrocephalus was seen in 21. Fourteen were in the lateral ventricle, and 10 were in the posterior fossa. Calcifications were present in five (all fourth ventricular) and absent in 10 (all lateral ventricular) subependymomas imaged with unenhanced CT. On 18 contrast-enhanced CT scans, five of six subependymomas with heterogeneous enhancement were in the fourth ventricle, and nine of 12 tumors with minimal or no enhancement were in the lateral ventricle. Small internal foci with a signal intensity similar to that of CSF were seen on images of all 10 lateral ventricular subependymomas obtained with both T1-weighted and T2-weighted sequences. On 13 contrast-enhanced T1-weighted images, seven of eight tumors with heterogeneous enhancement were in the fourth ventricle, and all five with minimal or no enhancement were in the lateral ventricle.

CONCLUSION

Intracranial subependymomas were seen in symptomatic middle-aged adults and showed different CT and MR imaging features, depending on their anatomic location. Calcification and heterogeneous contrast enhancement were common features of fourth ventricular subependymomas showed a lack of calcification as well as minimal or no contrast enhancement of CT and MR images.

Supratentorial ependymomas and subependymomas: CT and MR appearance

OBJECTIVE

Our goal was to characterize the CT and MR features of supratentorial ependymomas and subependymomas.

MATERIALS AND METHODS

The CT or MRI examinations of 11 supratentorial ependymomas (average patient age: 16 years) and 3 supratentorial subependymomas (average age: 60 years) were analyzed for tumor size, location, and appearance.

RESULTS

Ependymomas were periventricular (nine), intraventricular (one), or both (one) and averaged 4 cm in diameter. Four of nine ependymomas examined by CT were calcified. Eight ependymomas had a cystic component. All seven ependymomas evaluated with MRI demonstrated prolonged T1 and T2 relaxation, with two having foci thought to represent intratumoral hemorrhage. The MR contrast enhancement patterns included an enhancing nodule within the wall of a cyst (four), heterogeneous enhancement of cystic/solid lesions (two), and homogeneous enhancement of a solid lesion (one). All subependymomas were solid intraventricular masses, averaging 2.6 cm in diameter. One had small amounts of calcification, and none were cystic. All three were isointense or hypointense to white matter on T1-weighted MR images and heterogeneous or hyperintense on T2-weighted images, with variable enhancement characteristics. Early (< 1 year) postsurgical recurrence was seen in two ependymomas and one subependymoma.

CONCLUSION

Supratentorial ependymomas are typically large, cystic, calcified, extraventricular masses found in children and young adults. Supratentorial subependymomas are generally solid, intraventricular masses that are usually smaller than ependymomas and occur in an order patient population.

MRI of intracranial subependymomas

OBJECTIVE

We report imaging features of two cases of subependymoma, a relatively rare benign intraventricular neoplasm.

MATERIALS AND METHODS

The first case was a lateral ventricular tumor, which grew to a large size before becoming symptomatic. The second case was a fourth ventricular subependymoma with extensive cisternal spread.

RESULTS

In Case 1, absence of postcontrast enhancement suggested the correct diagnosis. However, in Case 2 heterogeneous enhancement made the diagnosis uncertain. In both cases, pre- and postoperative MRI was superior to other modalities in defining tumor extent and delineating the surrounding anatomy.

CONCLUSIONS

Magnetic resonance imaging is the modality of choice for studying subependymomas. The diagnosis should be placed among differential considerations for intraventricular tumors.

MR manifestations of subependymomas

PURPOSE

To provide a description of the MR and enhanced MR appearances of subependymomas.

METHODS

We reviewed the MR examinations of eight cases of pathologically proved subependymomas and correlated them with operative and pathologic reports, and also reviewed the previous published cases of subependymomas documented by MR. Gadopentetate dimeglumine-enhanced MR examination was performed in seven cases.

RESULTS

One patient presented with four subependymomas, two patients had subependymomas of the cervical spine, and the others were intraventricular with no transependymal extension. They were isointense to hypointense relative to normal white matter on T1-weighted images, heterogeneous in five cases. Minimal (n = 1) or no (n = 3) enhancement was noted in four cases, and moderate or marked enhancement was noted in three cases.

CONCLUSION

We conclude that even though there is no specific sign of subependymomas, when confronted with a complete intraventricular lesion or with a spinal lesion causing little or no edema which is minimally enhancing or nonenhancing, one must consider the diagnosis of subependymoma.

Familial occurrence of subependymoma. Report of two cases

Subependymomas are unusual tumors believed to arise from the bipotential subependymal cell. Previous reports of familial occurrence of subependymoma have involved monozygous twins and siblings. The authors describe the first reported occurrence of fourth ventricular subependymoma in a father and son, suggesting the possibility of direct inheritance.

Surgical treatment of symptomatic subependymoma of the nervous system. Report of five cases

Subependymomas are uncommon and relatively benign tumors with a distinctive histological appearance. They are generally asymptomatic and most of them are found incidentally at postmortem examination. These tumors are usually located in the fourth and lateral ventricle, and sometimes in the spinal cord. The authors present a series of 5 pure subependymomas of the central nervous system all of which were symptomatic and all of which were treated by microsurgical removal. The clinico-pathological findings and the results of microsurgical treatment in this series are presented.

[Clinical aspects and pathology of intracranial subependymoma--18 personal cases and review of the literature]

Intracranial subependymomas are rare, benign tumours (WHO grade I) occupying a special position compared to the other ependymal neoplasms. They often remain asymptomatic and, in consequence, are found incidentally at autopsy. In the present study clinico-pathological data of 84 symptomatic (8 own cases) and 58 asymptomatic tumours (10 own cases) are summarised. Subependymomas are more frequently situated in the fourth (58.4%) than in the lateral ventricle (38.0%). They occur predominantly in middle-aged and elderly males. Tumours in the lateral ventricles manifest themselves more often than those in the fourth ventricle. In general, asymptomatic subependymomas do not exceed a diameter of 1.2 cm. The nature of symptoms, with a median symptomatic period of 12 months, is usually associated with hydrocephalus, which is present in more than 80% of the symptom-producing subependymomas. Growth within the ventricular lumen and sharp demarcation from the surrounding brain tissue allow a complete removal in half of the cases. Radical extirpation can be achieved more often in patients with subependymomas located in the lateral ventricles than in those with tumours arising from the floor of the fourth ventricle. The high operative mortality, at a rate of 28.8% so far, mainly refers to the period before microsurgical technique was established. Recurrences are very rare, spinal seeding has not been found to date. For the assessment of long-term results further detailed compilation and documentation of individual follow-ups is necessary.