Biological behavior and tumorigenesis of subependymal giant cell astrocytomas

Bleeding solitary SEGA in non-tuberous sclerosis complex adolescent: a case illustration and review of literature

Subependymal giant cell astrocytoma (SEGA) represents a benign brain tumor occurring in 5-20% of individuals diagnosed with tuberous sclerosis complex (TSC), serving as a major diagnostic criterion. The presence of SEGA in a patient often prompts consideration of TSC as a probable diagnosis, given its unique association with this disorder. Typically, only one additional major criterion or two minor criteria are necessary to fulfill the diagnostic criteria for TSC. However, in rare instances, SEGA may manifest in patients without clinical features of TSC, termed solitary SEGA. The occurrence of solitary SEGA in patients lacking both clinical manifestations of TSC and genetic confirmation is extremely rare. Furthermore, the presentation of SEGA with intratumoral bleeding is exceedingly uncommon. Here, we presented a case of bleeding solitary SEGA in non-TSC adolescent who underwent surgery and has remained free of disease for a minimum of 3 years. Genetic analysis of peripheral blood and tumor tissue yielded negative results for TSC-related mutations. While SEGA occurrence in non-TSC patients is uncommon, it remains one of the possible diagnoses of intraventricular tumors. However, comprehensive genetic and physical evaluations are imperative to confirm the TSC status and guide further investigations and follow-up appropriately.

A rare case of subependymal giant cell astrocytoma presenting with spontaneous intratumoral hemorrhage

ABSTRACT

Subependymal giant cell astrocytomas (SEGAs) are low-grade gliomas usually arising in the periventricular regions near the foramen of Monro seen exclusively with tuberous sclerosis complex. Incidence of hemorrhage in SEGA is less than 1% with only 10 cases reported in English literature. We present a similar case of SEGA with spontaneous intratumoral hemorrhage in a 35-year-old male with cutaneous manifestations of tuberous sclerosis complex and acute onset headache with convulsion.

Subependymal Giant Cell Astrocytoma Apoplexy: A Case Report and Systematic Review

Subependymal giant cell astrocytoma (SEGA) is the most common intracranial tumor in tuberous sclerosis (TS) patients. The tumor generally localizes in the proximity of Monro's foramen; as it grows, it subsequently causes hydrocephalus and increases intracranial pressure (ICP). However, acute symptoms of increased ICP due to intratumoral bleeding rarely manifest in SEGA patients. We present a 27-year-old male with TS who presented due to hemorrhagic complications of SEGA with intratumoral bleeding and vitreous orbital hemorrhage. We then conducted a systematic review with four databases (PubMed, Web of Science, Google Scholar, and Cochrane) to identify similar cases using the following keywords: "Subependymal giant cell astrocytoma," "Hemorrhage," "Haemorrhage," and "Bleeding." Our review identified 12 articles reporting 14 cases of hemorrhagic complications of SEGA in addition to our case report. The median age of diagnosis was 21 (range 5-79) years with unequal gender distribution (M:F ratio, 11:4). Headache was the most presented symptom, followed by hemiparesis, seizure, altered mental status, visual deterioration, and headache accompanied by seizure. TS was seen in most of the cases (80%). Gross total resection (GTR) was achieved in 53.5% of the patients. Regarding the clinical outcome, 66.7% had a good outcome, 20% died, and 13.3% had no report of their outcomes. No tumor recurrence was seen in the cases with a reported duration of follow-up. Catastrophic presentation of SEGA apoplexy is a rare occurrence. We present a case report with a systematic review and discuss SEGA apoplexy's possible pathophysiology and outcome.

Subependymal giant-cell astrocytoma: a surgical review in the modern era of mTOR inhibitors

INTRODUCTION

Surgical removal has been the historical treatment for subependymal giant-cell astrocytoma (SEGA) in tuberous sclerosis complex (TSC) patients. In the past decade, mTOR inhibitors have shown efficacy in the treatment of SEGA, significantly reducing tumor size. The aim of this study was to assess the safety and efficacy of surgical treatment at a time when mTOR inhibitors have changed standard treatment.

MATERIAL AND METHODS

We conducted a single-center retrospective study including all patients treated by surgery for SEGA from October 2003 to September 2019, with a review of all SEGA surgical case series, following PRISMA guidelines. Research focused on demographics, surgical indications, surgical approach, use of CSF shunt, morbidity and mortality, resection quality, recurrence rate and treatment of recurrence, follow-up and long-term clinical status.

RESULTS

Eleven patients were included, with a median age at surgery of 16.0 years. Gross total resection was achieved in 8 patients (72%), with no permanent morbidity. One patient needed further surgery for tumor recurrence. Eighteen studies were reviewed, totaling 263 TSC patients affected by SEGA and 286 surgical procedures. Gross total resection was achieved in 81.1% of cases, mortality was 4.9% and permanent morbidity 6.1%. Tumor recurrence occurred in 11.5% of cases, and was secondary to partial tumor resection at first surgery in the majority of cases.

CONCLUSION

Surgical treatment of SEGA is still a valid and effective option. Morbidity is low and complete disappearance of SEGA can be achieved in selected cases.

Neurosurgical treatment of subependymal giant cell astrocytomas in tuberous sclerosis complex: a series of 44 surgical procedures in 31 patients

BACKGROUND

Subependymal giant cell astrocytomas (SEGA) are benign tumors characteristic of tuberous sclerosis complex (TSC) that may cause hydrocephalus. Various treatments are nowadays available as mTOR inhibitors or surgery. Surgery is still a valid option especially for symptomatic and larger tumors.

METHODS

From January 1994 to December 2015, 31 TSC patients harboring SEGA underwent surgery at the Department of Neurosurgery of the Meyer Pediatric Hospital, Florence. Indications for surgery were tumor size and location, growth and cystization/hemorrhage, and hydrocephalus. Clinical data, preoperative and postoperative MRI, recurrence rate, further surgical procedures, and related complications were analyzed.

RESULTS

A total of 44 surgeries were performed in 31 TSC patients affected by SEGA, achieving gross total removal (GTR) and subtotal removal (STR), respectively, in 36 and 8 patients. Recurrences occurred in 11 patients; 9 of them underwent further surgical procedures and 2 were treated with mTOR pathway inhibitors. Surgical morbidity and mortality were, respectively, 22.7% and 2.3%. After a mean follow-up of 4.9 years, 90% of patients were tumor-free with good neurological status in 93.3%; twelve (40%) had a ventriculo-peritoneal shunt (VPS) for hydrocephalus.

CONCLUSIONS

The present series confirms that the surgical approach, combined with mTOR inhibitors, is still a valid option for the treatment of SEGAs.

Infantile atypical subependymal giant cell astrocytoma

Subependymal giant cell astrocytoma is a benign WHO grade I intraventricular tumor arise in patients with tuberous sclerosis complex. Previous reported described histopathological predictors of more aggressive forms, terms atypical SEGA in infantile age group. Other reports showed possible transformation of SEGA into glioblastoma, or misdiagnosis as glioblastoma due to the presence of atypical histopathological features. Here, we report a case of an infant who presented with right frontal extraventricular SEGA and underwent craniotomy with complete resection. Eight months later, he presented with fast recurrence in same location with midline shift and subfalcine herniation. Histopathological description showed high grade features including Ki labeling index of 60%, atypical mitotic figures, cellular plemorphism and necrosis. We also discussed the possible presence of different entity (termed atypical SEGA) which may have more aggressive clinical course, with literature review of predictors of SEGA aggressiveness and possible transformation/misdiagnosis as glioblastoma.

Surgery for subependymal giant cell astrocytomas in children with tuberous sclerosis complex

OBJECTIVE

Subependymal giant cell astrocytomas (SEGAs) are low-grade intraventricular glial tumors that develop in 10-15% of patients with tuberous sclerosis complex; they often cause hydrocephalus and are potentially accessible to a surgical treatment. Our aim is to evaluate morbidity and results after surgery in symptomatic and asymptomatic patients.

METHOD

We present a retrospective series of 18 pediatric patients operated on for SEGA between 2006 and 2016 at our institution. We reviewed surgical indications, preoperative clinical and radiologic data, surgical management, and clinical and radiological follow-up.

RESULTS

Mean age at surgery was 10.7 years. The surgical decision was based on clinical signs of raised intracranial pressure due to hydrocephalus in 8 and on radiological findings without any clinical signs in the other 10 patients (increased in SEGA volume with or without ventricular enlargement). Surgical treatment consisted in a frontal trans-ventricular microsurgical approach in 17 patients and an endoscopic approach in 1. External ventricular drainage was placed in all the patients but 1. Ventriculoperitoneal shunting (VPS) became necessary in 6 patients, all of them presenting with a preoperative active hydrocephalus. Morbidity appeared very low with meningitis occurring in 1 patient. Resection was complete in 15 children with no recurrence during a mean follow-up of 5.25 years and incomplete in 3 requiring a second surgery.

CONCLUSION

Surgery of SEGA represents a very effective treatment with low morbidity and no mortality in the present series. In patients operated before the onset of clinical signs of hydrocephalus, internal VPS could be avoided whereas in others, an additional shunt surgery became necessary. This gives arguments in favor of a regular MRI surveillance in tuberous sclerosis complex patients with SEGA in order to best propose resective surgery once a growth of tumor and/or ventricular size have been confirmed but before raised intracranial pressure occurs.

Subependymal Giant Cell Astrocytoma Presenting with Tumoral Bleeding: A Case Report

We report a rare case of subependymal giant cell astrocytoma (SEGA) associated with tumoral bleeding in a pediatric patient without tuberous sclerosis complex (TSC). A 10-year-old girl presented with a 2-week history of an increasingly aggravating headache. Brain magnetic resonance imaging revealed an approximately 3.6-cm, well-defined, heterogeneously enhancing mass with multistage hemorrhages on the right-sided foramen of Monro. The tumor was completely resected using a transcallosal approach. Intraoperatively, the mass presented as a gray-colored firm tumor associated with acute and subacute hemorrhages. The origin of the mass was identified as the ventricular septum adjacent to the foramen of Monro. A pathological analysis revealed pleomorphic multinucleated eosinophilic tumor cells with abundant cytoplasm. These cells showed positive staining for the glial fibrillary acidic protein and S100 protein. A diagnosis of SEGA was established. The patient recovered without any neurological symptoms. There was no evidence of TSC. The radiological follow-up showed no recurrence for 2 years. This was a case of SEGA with intratumoral hemorrhage, for which a favorable outcome was achieved, without any neurological deficit after tumoral resection.

Subependymal Giant Cell Astrocytoma: Associated Hyperproteinorrhachia Causing Shunt Failures and Nonobstructive Hydrocephalus - Report of Successful Treatment with Long-term Follow-up

Subependymal giant cell astrocytomas (SEGAs) are histologically benign tumors most frequently associated with tuberous sclerosis complex (TSC). Despite their benign histopathological appearance, they may cause unfavorable outcomes due to their intraventricular location. Rarely, SEGA may be associated with hyperproteinorrhachia (high levels of proteins in the cerebrospinal fluid [CSF]), which causes malresorptive, communicating hydrocephalus; certainly, this scenario makes shunt obstruction likely in this patient population. In this report, we illustrate the case of hyperproteinorrhachia in an SEGA patient with known TSC, who presented repeatedly with shunt failure from proteinaceous shunt obstruction. Subsequent surgical resection of the main intraventricular lesion resulted in a dramatic drop in the CSF protein levels and has since prevented further shunt failures. Different treatment concepts and possible pathophysiology are discussed and the pertinent literature is reviewed.

Mammalian Target of Rapamycin Inhibitors and Life-Threatening Conditions in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a multisystem disease associated with an overall reduction in life expectancy due to the possible occurrence of different life-threatening conditions. Subjects affected by TSC are, in fact, at risk of hydrocephalus secondary to the growth of subependymal giant cell astrocytomas, or of sudden unexpected death in epilepsy. Other nonneurological life-threatening conditions include abdominal bleeding owing to renal angiomyolipomas rupture, renal insufficiency due to progressive parenchymal destruction by multiple cysts, pulmonary complications due to lymphangioleiomyomatosis, and cardiac failure or arrhythmias secondary to rhabdomyomas. In the last decades, there has been a great progress in understanding the pathophysiology of TSC-related manifestations, which are mainly linked to the hyperactivation of the so-called mammalian target of rapamycin (mTOR) pathway, as a consequence of the mutation in 1 of the 2 genes TSC1 or TSC2. This led to the development of new treatment strategies for this disease. In fact, it is now available as a biologically targeted therapy with everolimus, a selective mTOR inhibitor, which has been licensed in Europe and USA for the treatment of subependymal giant cell astrocytomas and angiomyolipomas in subjects with TSC. This drug also proved to benefit other TSC-related manifestations, including pulmonary lymphangioleiomyomatosis, cardiac rhabdomyomas, and presumably epileptic seizures. mTOR inhibitors are thus proving to be a systemic therapy able to simultaneously address different and potentially life-threatening complications, giving the hope of improving life expectation in individuals with TSC.

Direct medical costs for patients with tuberous sclerosis complex and surgical resection of subependymal giant cell astrocytoma: a US national cohort study

OBJECTIVE

To estimate direct medical costs for patients with tuberous sclerosis complex (TSC) and surgical resection of subependymal giant-cell astrocytoma (SEGA).

METHODS

This retrospective cohort study selected patients who had SEGA surgery and TSC claims between 2000-2011 from three large US nationwide claims databases. Selected patients were age 35 or less and had continuous health insurance in the year before and the year after their first SEGA surgery claim. The study examined the patients' demographic and clinical characteristics and estimated inpatient, outpatient, medication, and total medical costs paid by insurance companies for the pre-surgery year, post-surgery year, and other study periods, respectively. Repeated measures analysis and bootstrapping technique were used to assess the impact of the surgery on the direct medical costs.

RESULTS

Select patients (n = 47) had a mean baseline age of 11.6 years and 66% were male. Many had seizures (91.0%), hydrocephalus (59.6%), vision disorders (38.3%), stroke and hemiparesis (36.2%), and shunt (34.0%) in the pre-surgery year. The mean direct medical costs were $8543 (inpatient: $3770; outpatient: $3473; medication: $1300) for the pre-surgery year, and $85,397 (inpatient: $71,562; outpatient: $11,497; medication: $2338) for the post-surgery year. With the exclusion of the costs during the surgery month, the inpatient, outpatient, medication, and total costs in the post-surgery year were 1.6-4.3 times as much as the costs in the pre-surgery year (inpatient: 4.3:1; outpatient: 2.5:1; medication: 1.6:1; total: 3.1:1, p < 0.05). Repeated measures analysis with bootstrapping confirmed a link between the surgery and increases in direct medical costs (p < 0.05).

CONCLUSIONS

SEGA surgery had a substantial impact on direct medical costs. TSC patients with the surgery experienced significant post-surgery increases in their inpatient, outpatient, and medication costs. Additional research should be conducted to examine the surgery's cost-impact in a longer duration, or to compare the cost-effectiveness of the surgery vs other treatments.

Surgical treatment of subependymal giant cell astrocytoma in tuberous sclerosis complex patients

BACKGROUND

Subependymal giant cell astrocytoma is a brain tumor associated with tuberous sclerosis complex. There are two treatment options for subependymal giant cell astrocytomas: surgery or mammalian target of rapamycin inhibitor. The analysis of outcome of subependymal giant cell astrocytoma surgery may help characterize the patients who may benefit from pharmacotherapy.

METHODS

Sixty-four subependymal giant cell astrocytoma surgeries in 57 tuberous sclerosis complex patients with at least a 12-month follow-up were included in the study. The tumor size, age of the patients, mutation in the TSC1 or TSC2 gene, indication for the surgery, and postsurgical complications were analyzed.

RESULTS

The mean age of patients at surgery was 9.7 years. Mean follow-up after surgery was 63.7 months. Thirty-seven (57.8%) tumors were symptomatic and 27 (42.2%) were asymptomatic. Patients with TSC2 mutations developed subependymal giant cell astrocytoma at a significantly younger age than individuals with TSC1 mutations. Four patients (6.2% of all surgeries) died after surgery. Surgery-related complications were reported in 0%, 46%, 83%, 81%, and 67% of patients with tumors <2 cm, between 2 and 3 cm, between 3 and 4 cm, >4 cm, and bilateral subependymal giant cell astrocytomas, respectively, and were most common in children younger than 3 years of age. The most common complications included hemiparesis, hydrocephalus, hematoma, and cognitive decline.

CONCLUSIONS

Our study indicates that subependymal giant cell astrocytoma surgery is associated with significant risk in individuals with bilateral subependymal giant cell astrocytomas, tumors bigger than 2 cm, and in children younger than 3 years of age. Therefore, tuberous sclerosis complex patients should be thoroughly screened for subependymal giant cell astrocytoma growth, and early treatment should be considered in selected patients.

Subependymal giant cell astrocytoma: current concepts, management, and future directions

BACKGROUND

Subependymal giant cell astrocytoma (SEGA) is the most common central nervous system tumor in patients with tuberous sclerosis complex (TSC). SEGAs are generally benign, non-infiltrative lesions, but they can lead to intracranial hypertension, obstructive hydrocephalus, focal neurologic deficits, and even sudden death.

DISCUSSION

Surgical resection has been the standard treatment for SEGAs, and it is generally curative with complete resection. However, not all SEGAs are amenable to safe and complete resection. Gamma Knife stereotactic radiosurgery provides another treatment option as a primary or adjuvant treatment for SEGAs, but it has highly variable response effects with sporadic cases demonstrating its efficacy. Recently, biologically targeted pharmacotherapy with mammalian target of rapamycin (mTOR) inhibitors such as sirolimus and everolimus has provided a safe and efficacious treatment option for patients with SEGAs. However, SEGAs can recur few months after drug discontinuation, indicating that mTOR inhibitors may need to be continued to avoid recurrence. Further studies are needed to evaluate the advantages and adverse effects of long-term treatment with mTOR inhibitors. This review presents an overview of the current knowledge and particularly highlights the surgical and medical options of SEGAs in patients with TSC.

Congenital subependymal giant cell astrocytomas in patients with tuberous sclerosis complex

PURPOSE

Subependymal giant cell astrocytoma (SEGA) is a brain tumor associated with tuberous sclerosis complex (TSC). It usually grows in a second decade of life, but may develop in the first months of life. The aim of this work was to establish the incidence, clinical features, and outcome of congenital SEGA in TSC patients.

METHODS

Cohort of 452 TSC patients was reviewed to identify cases with growing or hydrocephalus producing SEGAs in the first 3 months of life. Clinical presentation, size of the tumor, growth rate, mutational analysis, treatment applied, and outcome were analyzed.

RESULTS

Ten (2.2 %) patients presented with SEGA in the first 3 months of life. All of them had documented SEGA growth and all developed hydrocephalus. In eight patients, mutational analysis was done, and in all of them, TSC2 gene mutations were identified. Mean maximum SEGA diameter at baseline was 21.8 mm. Mean SEGA growth rate observed postnatally was 2.78 mm per month and tended to be higher (5.43 mm per month) in patients with TSC2/PKD1 mutation than in other cases. Seven patients underwent SEGA surgery and surgery-related complications were observed in 57.1 % cases. One patient was successfully treated with everolimus as a primary treatment.

CONCLUSIONS

Congenital SEGA develops 2.2 % of TSC patients. Patients with TSC2 mutations, and especially with TSC2/PKD1 mutations, are more prone to develop SEGA earlier in childhood and should be screened for SEGA from birth. In young infants with SEGA, both surgery and mTOR inhibitor should be considered as a treatment option.

Identification of brain tumour initiating cells using the stem cell marker aldehyde dehydrogenase

Aldehyde dehydrogenase (ALDH) has been identified in stem cells from both normal and cancerous tissues. This study aimed to evaluate the potential of ALDH as a universal brain tumour initiating cell (BTIC) marker applicable to primary brain tumours and their biological role in maintaining stem cell status. Cells from various primary brain tumours (24paediatric and 6 adult brain tumours) were stained with Aldefluor and sorted by flow cytometry. We investigated the impact of ALDH expression on BTIC characteristics in vitro and on tumourigenic potential in vivo. Primary brain tumours showed universal expression of ALDH, with 0.3-28.9% of the cells in various tumours identified as ALDH(+). The proportion of CD133(+) cells within ALDH(+) is higher than ALDH cells. ALDH(+) cells generate neurospheres with high proliferative potential, express neural stem cell markers and differentiate into multiple nervous system lineages. ALDH(+) cells tend to show high expression of induced pluripotent stem cell-related genes. Notably, targeted knockdown of ALDH1 by shRNA interference in BTICs potently disturbed their self-renewing ability. After 3months, ALDH(+) cells gave rise to tumours in 93% of mice whereas ALDH cells did not. The characteristic pathology of mice brain tumours from ALDH(+) cells was similar to that of human brain tumours, and these cells are highly proliferative in vivo. Our data suggest that primary brain tumours contain distinct subpopulations of cells that have high expression levels of ALDH and BTIC characteristics. ALDH might be a potential therapeutic target applicable to primary brain tumours.

Long-term effect of everolimus on epilepsy and growth in children under 3 years of age treated for subependymal giant cell astrocytoma associated with tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC) is a genetic disorder characterized by increased mammalian target of rapamycin (mTOR) activation and growth of benign tumors in several organs throughout the body. In young children with TSC, drug-resistant epilepsy and subependymal giant cell astrocytomas (SEGAs) present the most common causes of mortality and morbidity. There are also some reports on the antiepileptic and antiepileptogenic potential of mTOR inhibitors in TSC. However, the data on everolimus efficacy and safety in young children are very limited.

AIMS

To show the long-term safety data and the effect of everolimus treatment on epilepsy in children under the age of 3 who received everolimus for SEGAs associated with TSC.

METHODS

We present the results of everolimus treatment in 8 children under the age of 3 who participated in EXIST-1 study. Five patients presented with active, drug-resistant epilepsy at baseline. The mean follow-up is 35 months (33-38 months) and all children are still on treatment.

RESULTS

In 6 out of 8 children, at least a 50% reduction in SEGA volume was observed. In 1 child with drug-resistant epilepsy, everolimus treatment resulted in cessation of seizures and in 2 other children, at least a 50% reduction in the number of seizures was noted. The incidence of adverse events (AE) was similar to that observed in older children and adults.

CONCLUSIONS

This study suggests that everolimus is effective and safe in infants and young children with epilepsy and SEGA associated with TSC and offers a valuable treatment option.

From the radiologic pathology archives: intraventricular neoplasms: radiologic-pathologic correlation

A variety of neoplasms may arise in the ventricular system. Intraventricular neoplasms may be discovered as an incidental finding at cross-sectional imaging or may manifest with varied symptoms depending on their location, including symptoms of increased intracranial pressure. These lesions may arise from various ventricular structures, including the ependymal lining (eg, ependymoma), subependymal layer (eg, subependymoma), or choroid plexus (eg, choroid plexus neoplasms), or they may have a cell of origin that has yet to be determined (eg, chordoid glioma). Other neoplasms involving the ventricular system include central neurocytoma, subependymal giant cell tumor, meningioma, rosette-forming glioneuronal tumor, and metastases. The differential diagnosis for intraventricular neoplasms can be broad, and many of them have similar patterns of signal intensity and contrast enhancement at imaging. However, the location of the lesion in the ventricular system-along with knowledge of the patient's age, gender, and underlying conditions-will help narrow the differential diagnosis.

mTOR signaling in neural stem cells: from basic biology to disease

The mammalian target of rapamycin (mTOR) pathway is a central controller of growth and homeostasis, and, as such, is implicated in disease states where growth is deregulated, namely cancer, metabolic diseases, and hamartoma syndromes like tuberous sclerosis complex (TSC). Accordingly, mTOR is also a pivotal regulator of the homeostasis of several distinct stem cell pools in which it finely tunes the balance between stem cell self-renewal and differentiation. mTOR hyperactivation in neural stem cells (NSCs) has been etiologically linked to the development of TSC-associated neurological lesions, such as brain hamartomas and benign tumors. Animal models generated by deletion of mTOR upstream regulators in different types of NSCs reproduce faithfully some of the TSC neurological alterations. Thus, mTOR dysregulation in NSCs seems to be responsible for the derangement of their homeostasis, thus leading to TSC development. Here we review recent advances in the molecular dissection of the mTOR cascade, its involvement in the maintenance of stem cell compartments, and in particular the implications of mTOR hyperactivation in NSCs in vivo and in vitro.

Subependymal giant cell astrocytoma with intratumoral hemorrhage

The authors report on 2 cases of subependymal giant cell astrocytoma (SEGA) with intratumoral hemorrhage causing acute hydrocephalus, necessitating emergent resection of the tumor. They review the literature and present their insights on the management of SEGA showing growth on serial imaging. Intratumoral hemorrhage causing acute hydrocephalus can occur not only in the pediatric ages but also in the early 20s in patients with SEGA. Awareness of this sequela is considered to be important in addressing surgical timing. The authors suggest early resection of the lesions when the evidence of growth has been confirmed, to prevent possible morbidity and mortality.

Subependymal giant cell astrocytoma associated with tuberous sclerosis presenting with intratumoral bleeding. Case report and review of literature

The authors describe a rare case of subependymal giant cell astrocytoma (SEGA) associated with tuberous sclerosis complex that presented with intratumoral bleeding with extension to the ventricles. The literature regarding intracranial hemorrhage of SEGA is reviewed and only five cases have been reported in the literature. We have not identified a histological feature associated with bleeding.

The molecular biology of WHO grade I astrocytomas

World Health Organization (WHO) grade I astrocytomas include pilocytic astrocytoma (PA) and subependymal giant cell astrocytoma (SEGA). As technologies in pharmacologic neo-adjuvant therapy continue to progress and as molecular characteristics are progressively recognized as potential markers of both clinically significant tumor subtypes and response to therapy, interest in the biology of these tumors has surged. An updated review of the current knowledge of the molecular biology of these tumors is needed. We conducted a Medline search to identify published literature discussing the molecular biology of grade I astrocytomas. We then summarized this literature and discuss it in a logical framework through which the complex biology of these tumors can be clearly understood. A comprehensive review of the molecular biology of WHO grade I astrocytomas is presented. The past several years have seen rapid progress in the level of understanding of PA in particular, but the molecular literature regarding both PA and SEGA remains nebulous, ambiguous, and occasionally contradictory. In this review we provide a comprehensive discussion of the current understanding of the chromosomal, genomic, and epigenomic features of both PA and SEGA and provide a logical framework in which these data can be more readily understood.

Advances in the management of subependymal giant cell astrocytoma

BACKGROUND

Subependymal giant cell astrocytoma (SEGA) is the most common central nervous system tumor in patients with tuberous sclerosis complex (TSC). Although these lesions are generally benign and non-infiltrative, they commonly arise in the region of the foramen of Monro, where they can cause obstructive hydrocephalus and sudden death.

METHODS

Surgical resection has been, and presently remains, the standard treatment for SEGAs demonstrating serial growth on neuroimaging in the setting of symptomatic hydrocephalus or progressive ventriculomegaly.

DISCUSSION

Surgery can be curative; however, not all SEGAs are amenable to safe and complete resection. Gamma Knife stereotactic radiosurgery provides another treatment option but has highly variable response rates with limited data demonstrating its efficacy. Newer medical therapy targeting mammalian target of rapamycin (mTOR), the key protein kinase that is constitutively activated in TSC, has demonstrated promising results in recent clinical trials. In both case reports and clinical trials, treatment with mTOR inhibitors results in a significant reduction in SEGA volume and improvement or resolution of ventriculomegaly. This has led to the approval of everolimus for the treatment of SEGA in tuberous sclerosis patients who are not candidates for surgery. This review summarizes the surgical and medical management of SEGA in patients with TSC.

Surgical resection of subependymal giant cell astrocytomas (SEGAs) and changes in SEGA-related conditions: a US national claims database study

OBJECTIVES

To compare the prevalence rates of clinical conditions related to subependymal giant cell astrocytomas (SEGAs) before and after SEGA surgery among patients with tuberous sclerosis complex (TSC).

METHODS

Based on three US national claims databases, we analyzed and compared the prevalence rates of 21 SEGA-related conditions (including seizures, hydrocephalus, headaches and stroke or hemiparesis) in the six months preceding surgery with the rates in the second through sixth post-surgery months and in the seventh through twelfth post-surgery months among TSC patients who underwent SEGA surgery during 2000-2009. Repeated measures analysis with a bootstrapping method was used to assess the surgery impact.

RESULTS

Patients (N = 47) had a mean age of 11.5 years at their first SEGA surgery, and 66% were male. Compared with the six months preceding surgery, the post-surgery prevalence rates increased by 23-26% for seizures, 21-26% for hydrocephalus, 17-19% for headache and 6-9% for stroke or hemiparesis (all p < 0.05). Repeated measures analysis confirmed the impact of surgery on the prevalence rate of these five conditions (all p < 0.05).

CONCLUSIONS

SEGA surgery has its important role in SEGA treatment. However, after SEGA surgery this group of TSC patients had increased prevalence rates of seizures, hydrocephalus, vision disorders, headaches, stroke or hemiparesis, and autism. Future research to examine the causes of these symptoms is imperative.

LIMITATIONS

The study results have limitations in data source representativeness, coding accuracy, and study design.

Outcomes of resecting subependymal giant cell astrocytoma (SEGA) among patients with SEGA-related tuberous sclerosis complex: a national claims database analysis

OBJECTIVE

To examine the outcomes following resection of subependymal giant cell astrocytoma (SEGA) among patients with SEGA-associated tuberous sclerosis complex (TSC).

METHODS

Using three large US national healthcare claims databases, we retrospectively examined the outcomes of SEGA surgery among TSC patients who underwent SEGA surgery between 2000 and 2009. The examined outcomes were: prevalence rates of post-surgery SEGA, repeated SEGA surgery, and postoperative complications (surgical procedure complications, nervous system complications, postoperative infections, complications of subdural empyemas, and complications of epidural abscesses). Descriptive data analysis and two-sided one sample t-test for mean or proportion were used to assess the characteristics of patients and the outcomes of SEGA surgery.

RESULTS

The selected patients (N = 47) had a mean age of 11.6 years at their first SEGA surgery and 66% were male. During the third through twelfth months following surgery, 34% had post-surgery SEGA (diagnosis) and 12% underwent repeated SEGA surgeries. During the first post-surgery year, 48.9% of patients developed postoperative complications (34.0% had complications relating to the surgical procedure, 12.8% had nervous system complications, 6.4% developed postoperative infections, 17.0% had complications of subdural empyemas, and 2.1% had complications of epidural abscesses).

CONCLUSIONS

SEGA surgery was associated with statistically significant risks of developing post-surgery SEGA, requiring repeated SEGA surgery and developing postoperative complications. Future efforts in reducing these outcomes, either through improving surgical procedures or through alternative treatments, are urgently needed.

LIMITATIONS

This study has its limitation in data source representativeness and measurement accuracy.

Tuberous sclerosis and epilepsy: role of astrocytes

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that is among the most common genetic causes of epilepsy. Focal brain lesions in TSC, known as cortical tubers, have been implicated in promoting epileptogenesis in TSC. Histological, cellular, and molecular abnormalities in astrocytes are characteristic features of tubers and perituberal cortex, suggesting that astrocyte dysfunction may contribute to the pathophysiology of epilepsy in TSC. Numerous astrocytes can be seen histologically in tubers expressing glial fibrillary acidic and S100 proteins. In some analyses, astrocytes exhibit enhanced activation of the mammalian target of rapamycin suggesting a link between TSC1 and TSC2 mutations and astrocytic proliferation. Astrocytic proliferation in subependymal giant cell astrocytoma is associated with progressive growth and compression of surrounding brain structures by these lesions. Increased numbers of enlarged astrocytes has been observed in several TSC mouse models and may be intimately linked to epileptogenesis. Impairment of astrocytic buffering mechanisms for glutamate and potassium has been identified in TSC animal models and human tuber tissue and likely promotes neuronal excitability and seizures in TSC. Targeting these defects in astrocytes may represent a novel therapeutic strategy for epilepsy in patients with TSC.

Effective everolimus treatment of inoperable, life-threatening subependymal giant cell astrocytoma and intractable epilepsy in a patient with tuberous sclerosis complex

We present successful everolimus treatment of a huge subependymal giant cell astrocytoma in a 10-year old boy with tuberous sclerosis complex. The patient underwent several partial tumor resections complicated by intraoperative cardiac arrest. The tumor has been regrowing and produced severe clinical symptoms. Everolimus treatment resulted in marked tumor regression, significant improvement in patient's ambulation and cessation of seizures. Moreover, the therapy was well tolerated. These findings indicate that everolimus treatment should be considered as a therapeutic option alternative to surgery in patients with tuberous sclerosis complex.

The management of subependymal giant cell tumors in tuberous sclerosis: a clinician's perspective

BACKGROUND

Tuberous sclerosis (TSC) is a genetic multisystem disorder associated with hamartomas in several organs including subependymal giant cell tumors (SGCT). SGCT have the potential to grow and therefore to become symptomatic and are one of the main causes of death in TSC individuals. Surgical resection is the procedure of choice for SGCT. However, the discovery of mTOR pathway upregulation in TSC-associated tumors and recent evidence that mTOR inhibitors may induce regression of SGCT open up new treatment strategies. Based on a review of the currently available literature and on personal experience, current options for the management of TSC patients and appropriate indications, taking into account benefits and risks of surgery and pharmacotherapy, are discussed.

DISCUSSION

An earlier diagnosis of SGCT in neurologically asymptomatic children may allow a precocious surgical removal of the tumor, thus minimizing surgery-related morbidity and mortality. Biologically targeted pharmacotherapy with mTOR inhibitors such as sirolimus and everolimus provides a safe and efficacious treatment option for patients with SGCT and has the potential to change the clinical management of these tumors. However, whether pharmacotherapy is sufficient to control growth or if it only delays the need for surgical removal of symptomatic SGCT remains unclear. Further studies are needed to determine the optimal levels of mTOR inhibitors that preserve maximal anti-tumor efficacy while minimizing side effects.

Enhanced epidermal growth factor, hepatocyte growth factor, and vascular endothelial growth factor expression in tuberous sclerosis complex

Epidermal growth factor (EGF), hepatocyte growth factor (HGF), and vascular endothelial growth factor (VEGF) regulate angiogenesis and cell growth in the developing brain. EGF, HGF, and VEGF modulate the activity of the mammalian target of rapamycin (mTOR) cascade, a pathway regulating cell growth that is aberrantly activated in tuberous sclerosis complex (TSC). We hypothesized that expression of EGF, HGF, VEGF, and their receptors EGFR, c-Met, and Flt-1, respectively, would be altered in TSC. We show by cDNA array and immunohistochemical analysis that EGF, EGFR, HGF, c-Met, and VEGF, but not Flt-1, mRNA, and protein expression was up-regulated in Tsc1 conditional knockout (Tsc1(GFAP)CKO) mouse cortex. Importantly, these alterations closely predicted enhanced expression of these proteins in tuber and subependymal giant cell astrocytoma (SEGA) specimens in TSC. Expression of EGF, EGFR, HGF, c-Met, and VEGF protein, as well as hypoxia inducible factor-1α, a transcription factor that regulates VEGF levels and is also modulated by mTOR cascade activity, was enhanced in SEGAs (n = 6) and tubers (n = 10) from 15 TSC patients. Enhanced expression of these growth factors and growth factor receptors in human SEGAs and tubers and in the Tsc1(GFAP)CKO mouse may account for enhanced cellular growth and proliferation in tubers and SEGAs and provides potential target molecules for therapeutic development in TSC.

Gamma Knife surgery for subependymal giant cell astrocytomas. Clinical article

OBJECT

The authors report their experience of using Gamma Knife surgery (GKS) in patients with subependymal giant cell astrocytoma (SEGA).

METHODS

Over a 20-year period, the authors identified 6 patients with SEGAs who were eligible for GKS. The median patient age was 16.5 years (range 7-55 years). In 4 patients, GKS was used as a primary management therapy. One patient underwent radiosurgery for recurrent tumors after prior resection, and in 1 patient GKS was used as an adjunct after subtotal resection. The median tumor volume at GKS was 2.75 cm(3) (range 0.7-5.9 cm(3)). A median radiation dose of 14 Gy (range 11-20 Gy) was delivered to the tumor margin.

RESULTS

The median follow-up duration was 73 months (range 42-90 months). Overall local tumor control was achieved in 4 tumors (67%) with progression-free periods of 24, 42, 57, and 66 months. Three tumors regressed and one remained unchanged. In 2 patients the tumors progressed, and in 1 of these patients the lesion was managed by repeated GKS with subsequent tumor regression. The other relatively large tumor (5.9 cm(3)) was excised 9 months after GKS. The progression-free period for all GKS-managed tumors varied from 9 to 66 months. There were no cases of hydrocephalus or GKS-related morbidity.

CONCLUSIONS

Gamma Knife surgery may be an additional minimally invasive management option for SEGA in a patient who harbors a small but progressively enlarging tumor when complete resection is not safely achievable. It may also benefit patients with a residual or recurrent tumor that has progressed after surgery.

Management of subependymal giant cell tumors in tuberous sclerosis complex: the neurosurgeon's perspective

BACKGROUND

Tuberous sclerosis complex (TSC), an autosomal dominant genetic disorder, can lead to the development of hamartomas in various organs, including the heart, lungs, kidneys, skin and brain. The management of subependymal giant cell tumors (SGCTs) is still controversial, and peri- and/or intraventricular neoplasms may lead to life-threatening hydrocephalus. In the last years, many progresses have been made in research into the tumorigenesis and behaviors of SGCTs. This review aims to clarify the specific role of neurosurgeons in the multidisciplinary management of SGCTs in children with TSC.

DATA SOURCES

Based on the recent scientific literature and personal experience, we reviewed the up-to-date data and discussed the trends in the management of SGCTs in children with TSC. The data were collected after a bibliography made using PubMed/Medline with these terms: subependymal, subependymal giant cell astrocytoma, subependymal giant cell tumor, and tuberous sclerosis complex.

RESULTS

SGCTs are shown to be generated from a glioneuronal lineage, but their filiation with subependymal nodules (SENs) is still under debate. While SENs may develop anywhere in the ventricular walls, SGCTs arise almost exclusively around the Monro foramina. In children with TSC, precise clinical and/or imaging criteria are mandatory to differentiate SENs that are always asymptomatic and riskless from SGCTs that have the potential to grow and therefore to obstruct cerebrospinal fluid pathways leading to hydrocephalus.

CONCLUSIONS

An earlier diagnosis of SGCT in neurologically asymptomatic children with TSC may allow a precocious surgical removal of the tumor before the installation of increased intracranial pressure signs, an attitude that is being progressively adopted to lessen the morbimortality rate.

Novel proteins regulated by mTOR in subependymal giant cell astrocytomas of patients with tuberous sclerosis complex and new therapeutic implications

Subependymal giant cell astrocytomas (SEGAs) are rare brain tumors associated with tuberous sclerosis complex (TSC), a disease caused by mutations in TSC1 or TSC2, resulting in enhancement of mammalian target of rapamycin (mTOR) activity, dysregulation of cell growth, and tumorigenesis. Signaling via mTOR plays a role in multifaceted genomic responses, but its effectors in the brain are largely unknown. Therefore, gene expression profiling on four SEGAs was performed with Affymetrix Human Genome arrays. Of the genes differentially expressed in TSC, 11 were validated by real-time PCR on independent tumor samples and 3 SEGA-derived cultures. Expression of several proteins was confirmed by immunohistochemistry. The differentially-regulated proteins were mainly involved in tumorigenesis and nervous system development. ANXA1, GPNMB, LTF, RND3, S100A11, SFRP4, and NPTX1 genes were likely to be mTOR effector genes in SEGA, as their expression was modulated by an mTOR inhibitor, rapamycin, in SEGA-derived cells. Inhibition of mTOR signaling affected size of cultured SEGA cells but had no influence on their proliferation, morphology, or migration, whereas inhibition of both mTOR and extracellular signal-regulated kinase signaling pathways led to significant alterations of these processes. For the first time, we identified genes related to the occurrence of SEGA and regulated by mTOR and demonstrated an effective modulation of SEGA growth by pharmacological inhibition of both mTOR and extracellular signal-regulated kinase signaling pathways, which could represent a novel therapeutic approach.

Congenital subependymal giant cell astrocytoma: clinical considerations and expression of radial glial cell markers in giant cells

OBJECTS

Congenital Subependymal giant cell astrocytoma (SEGA), diagnosed in fetal and neonatal period, is extremely rare. Previous studies have reported poor surgical outcomes of this small group of patients. We encountered a patient diagnosed as congenital SEGA and report the surgical outcome along with interesting immuno-phenotypes of giant tumor cells.

CASE

Ventriculomegaly and a hypoechoic mass near the foramen of Monro were detected in a fetus on prenatal ultrasonography in the 35th week of gestation. Surgery was scheduled 2 months later to reduce the risk of operative complications. At postnatal 2 months, gross total resection of the tumor was achieved without complications. The patient had been followed up for 1 year without tumor recurrence. In double immunofluorescence, the prototype cells of SEGA expressed a variety of neural stem cell (nestin and Sox2) and radial glial cell markers (vimentin and brain lipid-binding protein), in addition to glutamate/aspartate transporter and glial fibrillary acidic protein.

CONCLUSIONS

Congenital SEGA can be successfully treated with judicious use of observation period and careful evaluation of general conditions. Pathological findings support the concept that SEGA may originate from aberrant radial glial cells in the developing brain.

The pathogenesis and imaging of the tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal-dominant disorder characterized by the formation of hamartomatous lesions in multiple organ systems. It is the second most common neurocutaneous syndrome after neurofibromatosis type 1 and has been recognized since the late 1800s. Although the disease has complete penetrance, there is also high phenotypic variability: some patients have obvious signs at birth, while others remain undiagnosed for many years. In addition to skin lesions, TSC patients develop numerous brain lesions, angiomyolipoma (AMLs), lymphangiomyomatosis (LAM) in the lungs, cardiac rhabdomyomas, skeletal lesions, and vascular anomalies, all of which are well seen with medical imaging. Our knowledge of TSC genetics and pathophysiology has expanded dramatically in recent years: two genetic loci were discovered in the 1990s and recent elucidation of TSC's interaction with the mTOR pathway has changed how we manage the disease. Meanwhile, medical imaging is playing an increasingly important role in the diagnosis, management, and treatment of TSC. We provide an update on the genetics and pathophysiology of TSC, review its clinical manifestations, and explore the breadth of imaging features in each organ system, from prenatal detection of cardiac rhabdomyomas to monitoring rapamycin therapy to treatment of AMLs by interventional radiology.

[Phacomatosis and genetically determined tumors: the transition from childhood to adulthood]

Phacomatoses, or neurocutaneous disorders, are a group of congenital and hereditary diseases characterized by developmental lesions of the neuroectoderm, leading to pathologies affecting the skin and the central nervous system. There is a wide range of pathologies affecting individuals at different moments of life. The genetics is variable: while neurofibromatosis 1 and 2, tuberous sclerosis and von Hippel-Lindau disease are all inherited as autosomal dominant traits, Sturge-Weber syndrome is sporadic. Other neurocutaneous disorders can be inherited as autosomal recessive traits (i.e., ataxia-telangiectasia), X-linked (i.e., incontinentia pigmenti) or explained by mosaicism (i.e., hypomelanosis of Ito, McCune-Albright syndrome). In this review, we discuss the major types of neurocutaneous disorders most frequently encountered by the neurosurgeon and followed beyond childhood. They include neurofibromatosis types 1 and 2, tuberous sclerosis, Sturge-Weber syndrome and von Hippel-Lindau disease. In each case, a review of the literature, including diagnosis, genetics and treatment will be presented. The lifespan of the disease with the implications for neurosurgeons will be emphasized. A review of cases, including both pediatric and adult patients, seen in neurosurgical practices in the Lille, France and Lausanne, Switzerland hospitals between 1961 and 2007 is presented to illustrate the pathologies seen in different age-groups. Because the genes mutated in most phacomatoses are involved in development and are activated following a timed schedule, the phenotype of these diseases evolves with age. The implication of the neurosurgeon varies depending on the patient's age and pathology. While neurosurgeons tend to see pediatric patients affected with neurofibromatosis type 1, tuberous sclerosis and Sturge-Weber syndrome, there will be a majority of adult patients with von Hippel-Lindau disease or neurofibromatosis type 2.

The neurobiology of the tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a multisystem disorder that affects numerous organ systems. Brain lesions that form during development, known as tubers, are highly associated with epilepsy, cognitive disability, and autism. Following the identification of two genes and their encoded proteins, TSC1 (hamartin) and TSC2 (tuberin), responsible for TSC, identification of several downstream protein cascades that might be affected in TSC have been discovered. Of primary importance is the mammalian target of rapamycin pathway that controls cell growth and protein synthesis. The mechanisms governing brain lesion growth have not been fully identified but likely altered regulation of the mammalian target of rapamycin cascade by hamartin and tuberin during development leads to aberrant cell growth. Secondary effects of TSC gene mutations might disrupt normal neuronal migration and cerebral cortical lamination. Numerous studies have identified changes in gene and protein expression in animal models of TSC and in human TSC brain specimens that contribute to altered brain cytoarchitecture. This review will provide an overview of the neurobiological aspects of TSC.

Papilledema in obstructive hydrocephalus caused by giant cell astrocytoma of tuberous sclerosis

A 5-year-old girl with progressive hemiparesis and headache was found by brain imaging to have a large tumor centered at the foramen of Monro, blocking cerebrospinal outflow and producing massive lateral ventriculomegaly. Total excision of the mass led to a pathologic diagnosis of giant cell astrocytoma. Dermatologic abnormalities had been detected shortly after birth but were unexplained. Abdominal imaging disclosed renal cysts, and ophthalmologic examination disclosed papilledema and retinal plaques. On this basis, a diagnosis of tuberous sclerosis (TS) was finally made. Two months after surgery, papilledema had resolved, and visual function appeared to be normal. Although the patient apparently escaped visual loss, other reports affirm that giant cell astrocytoma, a common tumor in TS, may go undetected for long enough to produce irreversible optic neuropathy from chronic papilledema. Because patients with TS may not report visual loss, they should undergo periodic ophthalmologic screening.

Subependymal giant-cell astrocytomas in pediatric tuberous sclerosis disease: when should we operate?

OBJECTIVE

A small percentage of tuberous sclerosis patients will develop a subependymal giant-cell astrocytoma. Given the morbidity and mortality when such a lesion is left undiagnosed, successive follow-up imaging in pediatric patients has been recommended. Surgical removal of the lesion has become the procedure of choice; however, the timing of this surgery is still a controversial subject. By analyzing our own series of data, as well as other published series, we have attempted to reach a consensus on the benefits of early versus late surgery.

METHODS

We retrospectively reviewed 19 patients treated surgically for intraventricular tumors in Foch Hospital and at the Fondation Adolphe de Rothschild in Paris, France, and we analyzed published pediatric reports from 1980 to 2006.

RESULTS

The results from our own population, as well as from other published pediatric series (15 series), indicate that subependymal giant-cell astrocytomas have a good prognosis when a macroscopically total resection has been performed. In our series, residual lesions tended to enlarge, but residual tumors remaining stable have been reported. Careful follow-up examination should be undertaken because late recurrences do occur. Larger or symptomatic lesions tend to have a higher morbidity.

CONCLUSION

We think that any lesion fulfilling the criteria for a subependymal giant-cell astrocytoma as previously described in the literature (lesion around the foramen of Monro, greater than 5 mm, with incomplete calcifications) should be removed as soon as clear evidence of growth has been confirmed.

Immunohistochemical study of central neurocytoma, subependymoma, and subependymal giant cell astrocytoma

For investigation of histogenesis of central neurocytomas (CNs), subependymoma (SEs), subependymal giant cell astrocytomas (SEGAs), we studied expression of various neuronal and glial biomarkers by immunohistochemical (IHC) study and reverse transcriptase-polymerase chain reaction (RT-PCR). The materials for IHC were paraffin section of seven CNs, three SEs, and eight SEGAs and those for RT-PCR were frozen tissues of seven CNs, three SEs, and five SEGAs. Control group was five ependymomas (EPs) and four pilocytic astrocytomas (PAs). The neuronal biomarkers included nestin, chromogranin A (chrA), synaptophysin (SNP), neuronal cell adhesion molecule (NCAM), neuron specific enolase (NSE), neuronal nuclear antigen (NeuN), neurofilament (NF) and the glial marker was GFAP. CNs expressed all neuronal markers except NF (0%), SNP (100%), NCAM (100%), NSE (100%), NeuN (100%), nestin (29%) and chrA (43%), but GFAP expression was found only in one case (14%). SEGA coexpressed several neuronal markers and a glial marker; NeuN (100%), NSE (88%), NCAM (63%), nestin (100%), SNP (weakly and focally, 100%), and GFAP (100%), however, other neuronal markers including chrA, SNP and NF were all negative. SE expressed nonspecific neuronal markers (NCAM (100%) and NSE (100%)) which showed weak intensity and a GFAP (100%), but not nestin. Among control cases of EPs and PAs, no one case expressed neuronal markers except nonspecific neuronal marker of NCAM, but robustly expressed GFAP. RT-PCR product of nestin was expressed in 29% of CNs (2/7cases), 60% of SEGAs (3/5 cases), 100% of SEs (3/3 cases), 80% of EPs (4/5 cases), and 25% of PAs (1/4 cases). Conclusively, coexpression of neuronal and glial markers and expression of nestin in CNs, SEGAs and SEs suggested the origin of these tumor cells might be the stem cells being able to differentiate into both neuronal and glial phenotypes. But CNs might be originated from rather neuronally committed stem cells and SEs from rather glially committed stem cells.

Pathogenesis of tuberous sclerosis subependymal giant cell astrocytomas: biallelic inactivation of TSC1 or TSC2 leads to mTOR activation

In the central nervous system, tuberous sclerosis complex (TSC) is characterized by a range of lesions including cortical tubers, white matter heterotopias, subependymal nodules, and subependymal giant cell astrocytomas (SEGAs). Recent studies have implicated an important role for the TSC genes TSC1 and TSC2, in a signaling pathway involving the mammalian target of rapamycin (mTOR) kinase. We performed immunohistochemical and genetic analyses on SEGAs from 7 TSC patients, 4 with mutations in TSC1, and 3 with mutations in TSC2. SEGA cells show high levels of phospho-S6K, phospho-S6, and phospho-Stat3, all proteins downstream of and indicative of mTOR activation. Such expression is not seen in histologically normal control tissue. Five of 6 SEGAs also showed evidence of biallelic mutation of TSC1 or TSC2, suggesting that SEGAs develop due to complete loss of a functional tuberin-hamartin complex. We conclude that TSC SEGAs likely arise through a two-hit mechanism of biallelic inactivation of TSC1 or TSC2, leading to activation of the mTOR kinase.

The phakomatoses

The "phakomatosis" concept was formulated early in the twentieth century by the ophthalmologist van der Hoeve. He included 3 disorders in the group-neurofibromatosis, tuberous sclerosis complex, and von Hippel-Lindau syndrome--on the basis of the occurrence of patchy ophthalmologic manifestations in each disorder. Since the name was coined, much has been learned about the pathogenesis of these 3 disorders. It is clear that 2 of them--neurofibromatosis and tuberous sclerosis--are collective terms for multiple disorders. Each of the conditions is caused by distinct genetic defects, with little commonality in terms of protein function. Yet, in some respects, the disorders share a pathogenetic mechanism, that of the tumor suppressor gene. This review will briefly describe these disorders in light of what has been learned about underlying molecular pathogenesis. In each case, genetic testing is beginning to be available; principles of the use of genetic tests will be described.

Subependymal giant cell astrocytoma: a report of five cases

Five cases of intraventricular subependymal giant cell astrocytomas (SEGCA) were retrospectively reviewed. Records and detailed work-up of all five cases were well maintained in view of rare occurrence of these tumors. The five patients were males aged 10, 12 (2 cases), 14 and 18 years. The 18-year-old aged male had no stigmata of tuberous sclerosis (TSC) on examination, while the rest presented with features of TSC, intraventricular tumors and hydrocephalus. None of the five cases had renal tumors and did not reveal cardiac tumors. Skin manifestations like shagreen patches were present in two, facial angiofibromas in three, periungal fibromas in two, hypopigmented macules in two and ash-leaf spot in two patients. Fundoscopic examination revealed retinal astrocytomas in two cases only. Two of the five children did not have mental compromise. A child who started throwing seizures early (at 5 months of age) had severe mental retardation. Although SEGCA is a less vascular tumor, one tumor bled profusely intraoperatively; it was excised rapidly via the transcortical route to salvage the life of the child, though he was planned for the transcallosal route like the other cases. The tumor of another child was also very vascular. Four children survived surgery and required no shunt CSF diversion, while one died of severe ventriculitis and septicemia 3 weeks after surgery.

Subependymal giant cell astrocytoma: a clinicopathological study of 23 cases with special emphasis on proliferative markers and expression of p53 and retinoblastoma gene proteins

AIMS

To gain a better insight into the biological behaviour of subependymal giant cell astrocytoma (SEGA), tumour suppressor gene protein expression and various proliferative indices were studied in these tumours and correlated with histological features and clinical outcome.

METHODS

We studied 23 cases of SEGA, 19 from our own Institute and four from the National Institute of Mental Health and Neurological Sciences (NIMHANS), Bangalore, India. Immunohistochemical staining for various glial and neuronal markers, proliferative markers (MIB-1, Topoisomerase II alpha PCNA) and tumour suppressor gene protein expression of p53 and retinoblastoma (Rb) were performed.

RESULTS

Nineteen cases of SEGA were collected over a period of 23 years (January 1978-December 2001), which accounted for 0.16% of all intracranial tumours and 0.51% of all gliomas reported at this centre. Ages ranged from 4 to 37 years (mean 13.2 years) with a male preponderance. Nine of the 23 cases were associated with tuberous sclerosis (TS), six at the time of diagnosis, while three developed TS during the follow-up period. Treatment consisted of surgical resection (total in nine cases and subtotal in 14 cases) followed by radiotherapy in seven cases. Except for two patients who died in the immediate post-operative period of surgical complications, the remaining patients were all alive in the follow-up period (mean 37.1 months). One patient experienced recurrence 22 years after the first surgery and a second patient after 2 years. Necrosis and/or mitoses were observed in five cases. Immunohistochemically, tumours were positive for both glial and neuronal markers. Interspersed inflammatory cells were a mixture of mast cells and lymphocytes of T immunophenotype. The MIB-1 labelling index (LI) ranged from 0 to 8% (mean 3.0%), topoisomerase II alpha (topo II alpha) LI from 0 to 9.5% (mean 2.9%) and PCNA LI from 10 to 59% (mean 32.5%). The difference in the labelling indices of tumours with and without mitoses and/or necrosis was not statistically significant. None of the tumours revealed loss of Rb gene protein expression. p53 immunopositivity was seen in 14 cases (labelling indices ranged from 1 to 7.3% with a mean of 2.4%). The correlation between the MIB-1 LI and topo II alpha LI, and topo II alpha LI and PCNA LI was significant (P<0.05) but not so with other parameters like p53 protein expression, duration of survival and morphological features such as mitoses and necrosis.

CONCLUSIONS

SEGAs are rare intraventricular tumours associated with TS and express both neuronal and glial markers. They have a low proliferative potential. Mitoses and necrosis are not associated with a worse prognosis. In view of the low proliferative indices and long survival of these patients without recurrence, the role of post-operative radiotherapy is questionable. These patients should be followed up closely as many of them develop stigmata of tuberous sclerosis at a later stage.

Multidrug resistance proteins in tuberous sclerosis and refractory epilepsy

Tuberous sclerosis is an autosomal dominant syndrome characterized by seizures that are refractory to medication in severely affected individuals. The mechanism involved in drug resistance in tuberous sclerosis is unknown. The proteins MDR-1 (multidrug resistance) and MRP-1 (multidrug resistance-associated protein-1) are linked to chemotherapy resistance in tumor cells. However, the relationship between refractoriness to antiepileptic drugs and MDR-1 or MRP-1 brain expression has been poorly studied. We have previously described a case of tuberous sclerosis with refractory epilepsy that expressed multidrug resistance gene (MDR-1) in tuber cells from epileptogenic brain lesion. In this retrospective study, we describe the expression of MDR-1 and MRP-1 in the epileptogenic cortical tubers of three pediatric patients with tuberous sclerosis and refractory epilepsy surgically treated. Monoclonal antibodies for MDR-1 and MRP-1 proteins were used for immunohistochemistry. In epileptogenic cortical tuber brain specimens, MDR-1 and MRP-1 proteins were strongly immunoreactive in abnormal balloon cells, dysplastic neurons, astrocytes, microglial cells, and some blood-brain vessels. A more extensive MDR-1 immunoreactivity was observed. These data suggest that refractory epilepsy phenotype in tuberous sclerosis can be associated with the expression of both multidrug resistance MDR-1 and MRP-1 transporters in epileptogenic cortical tubers.

Tuberin and hamartin expression is reduced in the majority of subependymal giant cell astrocytomas in tuberous sclerosis complex consistent with a two-hit model of pathogenesis

Subependymal giant cell astrocytomas are distinctive brain tumors that are seen only in tuberous sclerosis complex. Although histologically benign, they cause both moribidity and occasional mortality owing to progressive growth in some patients. Tuberous sclerosis complex is an autosomal dominant genetic disorder with a high sporadic case rate that is due to mutations in either of two genes, TSC1 and TSC2, encoding hamartin and tuberin, respectively. The pathogenesis of subependymal giant cell astrocytomas in tuberous sclerosis complex is uncertain. In this study, we examined the expression of tuberin and hamartin in subependymal giant cell astrocytomas from nine patients with tuberous sclerosis complex by immunohistochemistry with confocal microscopy. Loss of hamartin expression was seen in all subependymal giant cell astrocytomas, including five from patients with germline TSC2 mutations and two from patients with germline TSC1 mutations. The subependymal giant cell astrocytomas of six of nine patients had no expression of tuberin as well, whereas three patients retained some tuberin expression. Tuberin expression was seen in one patient with a TSC2 germline mutation and two patients whose mutational status was not determined. Overall, these data indicate a loss of both tuberin and hamartin expression in the subependymal giant cell astrocytomas of patients with both TSC1 and TSC2 mutations and are consistent with a two-hit disease pathogenesis model for the development of subependymal giant cell astrocytomas.

Intramedullary spinal cord astrolipoma: case report

OBJECTIVE AND IMPORTANCE

Reported is a case of a thoracic intramedullary astrocytoma with a lipomatous component, a so-called astrolipoma. This is the only known case of a single intraspinal astrolipoma in an otherwise healthy patient.

CLINICAL PRESENTATION

The patient was a 36-year-old woman with dorsal thoracic pain of more than 1 month's duration, mild lower extremity weakness, and incomplete sensory loss to the T10 level.

INTERVENTION

Magnetic resonance imaging of the thoracolumbar spine revealed a fusiform mass at the T9-T11 level. The patient underwent T9-T11 laminectomies and complete resection of the tumor. In the initial postoperative period, the patient's symptoms worsened. However, 3 months after surgery, the patient was clinically improved and was able to walk without assistance. Twelve months after surgery, imaging revealed no evidence of tumor.

CONCLUSION

The current treatment plan and recommendation, assuming this tumor will behave like a low-grade glioma or lipoma, is continued radiographic surveillance after gross total resection. Reresection is recommended for tumor recurrence or significant regrowth. The long-term prognosis for astrolipoma is unknown.

Subependymal Giant Cell Astrocytoma With Positive Tuberin Expression -Case Report-

An 11-year-old male presented with subependymal giant cell astrocytoma (SEGA) without other manifestations of tuberous sclerosis such as facial angiofibroma, epilepsy, or mental retardation. The diagnosis was "possible tuberous sclerosis complex" (TSC). Total resection of the tumor was performed. Immunohistochemical study revealed positive tuberin expression. In general, loss of tuberin is thought to be critical to the TSC phenotype. Our case demonstrated clear expression of tuberin in the SEGA specimen.

Rapid regrowth of solitary subependymal giant cell astrocytoma--case report

A 48-year-old female presented with a subependymal giant cell astrocytoma (SEGA) without tuberous sclerosis manifesting as memory and mental disturbance. Magnetic resonance imaging showed a huge mass which was well-demarcated and extended from the anterior horn of the right lateral ventricle to the septal area on the right side. Surgery was performed with partial removal of the tumor. The histological diagnosis was typical SEGA. One year postoperatively, follow-up magnetic resonance imaging revealed marked regrowth of the tumor. Total resection of the tumor was performed. Microscopic and immunohistochemical studies could not identify the cause of the rapid regrowth. SEGA can regrow rapidly after partial removal of the tumor.