20 Questions
What is the typical location of Subependymal giant cell astrocytoma (SEGA)?
Lateral ventricles adjacent to the foramen of Monro
What is a rare acute manifestation of Subependymal giant cell astrocytoma (SEGA)?
Massive spontaneous haemorrhage
What is the ICD-O coding for Subependymal giant cell astrocytoma (SEGA)?
9384/1
What is the CNS WHO grade of Subependymal giant cell astrocytoma (SEGA)?
Grade 1
What is the name of the editor responsible for Subependymal giant cell astrocytoma (SEGA)?
Guido Reifenberger
What is the typical location of SEGAs on CT scans?
In the lateral ventricles, near the foramen of Monro
What is the incidence rate of SEGA among patients with Tuberous Sclerosis?
5-15%
What is the role of mTOR inhibitors in the treatment of SEGA?
They reduce tumour volume
What is the distinguishing feature between SEGA and SEN?
Size, with SEGAs being ≥ 5 mm and SENs being < 5 mm
What is the genetic profile of SEGAs?
SEGAs have a strong association with Tuberous Sclerosis and show evidence of biallelic inactivation of TSC1 or TSC2
What is the characteristic appearance of SEGAs in terms of their location?
They arise from the wall of the lateral ventricle, close to the foramen of Monro.
What is the average Ki-67 proliferation index in SEGAs?
3%
What is the characteristic histopathological feature of SEGAs?
Circumscribed, moderately cellular tumours with a wide spectrum of glial phenotypes.
What is the frequent immunohistochemical feature of SEGAs?
Uniform and intense immunoreactivity for S100.
What is the rare complication of SEGAs?
Craniospinal dissemination.
What is the primary immunohistochemical feature that helps differentiate SEGA from its morphological mimics?
Nuclear immunoreactivity for TTF1
What ultrastructural feature may be detectable in SEGA cells?
Microtubules
In which situations may DNA methylome profiling be helpful in establishing the diagnosis of SEGA?
In histologically ambiguous cases
What is associated with optimal outcome in patients with SEGA?
Early detection and treatment
What has been reported to result in significant reduction of tumour size and control of SEGA progression?
Inhibition of mTOR with everolimus
Study Notes
Subependymal Giant Cell Astrocytoma (SEGA)
Definition
- A periventricular tumor composed partly of large ganglion-like astrocytes, strongly associated with tuberous sclerosis (TS) (CNS WHO grade 1)
ICD-O and ICD-11 Coding
- ICD-O: 9384/1
- ICD-11: 2A00.0Y & XH1L48
Localization
- Typically arise from the subependymal tissue of the lateral ventricles adjacent to the foramen of Monro
- Rare locations include the third ventricle and the retina
Clinical Features
- Most patients present with signs and symptoms of increased intracranial pressure
- Tumor growth at the foramen of Monro can block cerebrospinal fluid circulation, leading to obstructive hydrocephalus
- Massive spontaneous hemorrhage may be an acute manifestation
- Growth of subependymal nodule(s) (SENs) into a SEGA is usually a gradual process
Imaging
- On CT, SEGAs appear as solid, partially calcified masses located in the walls of the lateral ventricles
- On MRI, the tumors are usually heterogeneous, isointense, or slightly hypointense on T1-weighted images, and hyperintense on T2-weighted images, with marked contrast enhancement
Epidemiology
- SEGA is the most common CNS neoplasm in patients with TS
- Incidence rate of SEGA among patients with TS is 5–15%
- Calculated overall incidence of SEGAs in the US Surveillance, Epidemiology, and End Results Program (SEER) 18 database is 0.027 cases per 100 000 person-years
Etiology
- SEGA has a strong association with inherited TS
- Evidence of biallelic inactivation of the TSC1 or TSC2 gene supports the hypothesis that SEGAs arise as a consequence of a second-hit mechanism
Pathogenesis
- Activation of the mTOR pathway has been shown in SEGAs, and clinical trials have shown reductions in tumor volumes using mTOR inhibitors
- Cell of origin: SEGAs demonstrate glial, neuronal, and mixed neuroglial features, suggesting a cell of origin with the capacity to undergo differentiation along glial, neuronal, and neuroendocrine lines
This quiz covers topics related to brain and CNS tumors, including ICD-O and ICD-11 coding, clinical features, epidemiology, etiology, and more.
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