A case of subependymal giant cell astrocytoma without tuberous sclerosis complex and review of the literature

Subependymal Giant Cell Astrocytoma: The Molecular Landscape and Treatment Advances

Subependymal giant cell astrocytoma (SEGA) is most often found in patients with TSC (Tuberous Sclerosis Complex). Although it has been classified as a benign tumor, it may create a serious medical problem leading to grave consequences, including young patient demise. Surgery and chemotherapy belong to the gold standard of treatment. A broader pharmacological approach involves the ever-growing number of rapalogs and ATP-competitive inhibitors, as well as compounds targeting other kinases, such as dual PI3K/mTOR inhibitors and CK2 kinase inhibitors. Novel approaches may utilize noncoding RNA-based therapeutics and are extensively investigated to this end. The purpose of our review was to characterize SEGA and discuss the latest trends in the diagnosis and therapy of this disease.

The Clinicopathological Features of the Solitary Subependymal Giant Cell Astrocytoma: A Systematic Review

Subependymal giant cell astrocytoma (SEGA), a circumscribed grade I glioma, is typically associated with tuberous sclerosis complex (TSC). However, "solitary SEGA" has been described. We performed a systematic review of available case reports and case series of solitary SEGA. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was used with the following MeSH terms: "Subependymal giant cell astrocytoma," "Sporadic," "Absence," "Non-associated," "Solitary," and "Tuberous Sclerosis." Data sources included PubMed, Google Scholar, Web of Science, and Cochrane from 1979 to June 29, 2023. Of the 546 studies, 20 met the inclusion criteria. Fifty-nine cases were analyzed. The mean age was 19 years (range 4-75), with 29 women (49.1%). Tumor ranged in size from 0.8 to 5.8 cm. Headache was the most frequent initial symptom (75.6%). The lateral ventricles near the foramen of Monro were the most common location (66.10%). Tumors expressed neuroglial (n = 19) or only glial (n = 20) markers. In nine of 59 cases, genetic studies ruled out germinal TSC1/2 mutations; in 13 cases (22.03%), somatic mutations in those genes were identified. "Solitary SEGAs" included tumors with neuroglial profile and classic morphological pattern, and tumors with only glial markers. It is necessary to confirm in SEGA-like tumors, the dual nature with at least glial fibrillary acidic protein (GFAP), neurofilaments, and synaptophysin antibodies. Screening for TSC1/2 mutations, and probably of the NF type 1 gene, is recommended for both germline and somatic mutations. Long-term clinical follow-up is necessary to analyze biological behavior and compare it with genetic and molecular profiles.

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.

Imaging of supratentorial intraventricular masses in children: a pictorial review-part 2

PURPOSE

This article is the second in a two-part series aimed at exploring the spectrum of supratentorial intraventricular masses in children. In particular, this part delves into masses originating from cells of the ventricular lining, those within the septum pellucidum, and brain parenchyma cells extending into the ventricles. The aim of this series is to offer a comprehensive understanding of these supratentorial intraventricular masses, encompassing their primary clinical findings and histological definitions.

METHODS

We conducted a review and analysis of relevant epidemiological data, the current genetics/molecular classifications as per the fifth edition of the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (WHO CNS5), and imaging findings. Each supratentorial intraventricular mass was individually evaluated, with a detailed discussion on its clinical and histological features.

RESULTS

This article covers a range of supratentorial intraventricular masses observed in children. These include colloid cysts, subependymal giant cell astrocytomas, ependymomas, gangliogliomas, myxoid glioneuronal tumors, central neurocytomas, high-grade gliomas, pilocytic astrocytomas, cavernous malformations, and other embryonal tumors. Each mass type is characterized both clinically and histologically, offering an in-depth review of their individual imaging characteristics.

CONCLUSION

The WHO CNS5 introduces notable changes, emphasizing the vital importance of molecular diagnostics in classifying pediatric central nervous system tumors. These foundational shifts have significant potential to impact management strategies and, as a result, the outcomes of intraventricular masses in children.

Isolated subependymal giant cell astrocytoma (SEGA) in the absence of clinical tuberous sclerosis: two case reports and literature review

PURPOSE

Subependymal giant cell astrocytoma (SEGA) is a WHO grade I pediatric glioma arising in 5-15% of patients with tuberous sclerosis (TSC). Rare cases of isolated SEGA without TSC have been described. The etiology, genetic mechanisms, natural history, and response to treatment of these lesions are currently unknown. We describe two such cases of isolated SEGA with follow-up.

METHODS

Retrospective review was performed at a single institution to describe the clinical course of pathology-confirmed SEGA in patients with germline testing negative for TSC mutations.

RESULTS

Two cases of isolated SEGA were identified. Genetic analysis of the tumor specimen was available for one, which revealed an 18 base pair deletion in TSC1. Both cases were managed with surgical resection, one with preoperative embolization. In spite of a gross total resection, one patient experienced recurrence after three years. Treatment with an mTOR inhibitor led to a significant interval reduction of the mass on follow-up MRI. The patient tolerated the medication well for 6 years and is now off of treatment for 2 years with a stable lesion.

CONCLUSION

Cases of SEGA outside of the context of TSC are exceedingly rare, with only 48 cases previously described. The genetic mechanisms and treatment response of these lesions are poorly understood. To date, these lesions appear to respond well to mTOR inhibitors and may behave similarly to SEGAs associated with TSC. However, given that experience is extremely limited, these cases should be followed long term to better understand their natural history and treatment response.

TSC2 somatic mosaic mutation, including extra-tumor tissue, may be the developmental cause of solitary subependymal giant cell astrocytoma

PURPOSE

Subependymal giant cell astrocytomas (SEGAs) are tumors that usually arise in the wall of one or the other lateral ventricle near a foramen of Monro, most often on a background of tuberous sclerosis complex (TSC). TSC has a variety of clinical manifestations caused by germline mutations of the TSC complex subunit 1 or 2 (TSC1, TSC2) genes. SEGAs without clinical manifestations of TSC are termed solitary SEGAs, which are hypothesized to be caused by tumor-only TSC1/2 mutations, or "forme fruste" of TSC with somatic mosaic mutations. However, it is difficult to distinguish between the two. Here, we report three patients with genetically investigated solitary SEGAs and review this rare manifestation.

METHODS

SEGA was completely removed in two patients and partially removed in one. Genetic analyses were performed on the tumor tissue and on peripheral blood via DNA microarray, reverse-transcriptase polymerase chain reaction, and next-generation sequencing with ultra-deep sequencing of mutation points.

RESULTS

All three patients had tumors with TSC2 somatic mutations and loss of heterozygosity (LOH). In one patient, the same TSC2 mutation was also detected in 1% of leukocytes in his blood. The tumors did not recur, and clinical manifestations of TSC did not develop during the 4-year follow-up.

CONCLUSIONS

The genetic cause of solitary SEGAs may be a TSC2 mutation with LOH. In patients with solitary SEGA, mosaic mutations may present in other organs, and TSC may clinically manifest later in life; therefore, patients should be followed up for prolonged periods.