November 2022
A 3-year-old girl with developmental delay presents with seizures refractory to multiple antiepileptics.
Angiocentric Glioma, WHO Grade I
- Hospital Course:
- A 3-year-old girl with refractory seizures despite multiple trials with different antiepileptics
- Brain MRI revealed a nonenhancing, T1-hypointense, T2-hyperintense expansile mass in the left putamen, extending to the left anterior subinsular white matter and globus pallidus, measuring 18 x 17 x 19 mm.
- Subsequent PET/MRI demonstrated focal hypometabolism at the site of the left basal ganglia mass.
- For definitive diagnosis, a left frontal stereotactic brain biopsy was performed.
- Histopathologic findings from the biopsy revealed bipolar cells with oval spindled nuclei arranged around blood vessels, with some tumor cells oriented perpendicularly around blood vessels.
- The biopsy sample was positive for MYB-QKI fusion, a finding consistent with angiocentric glioma.
- Multidisciplinary conference discussion suggested this mass was not likely causative for this child’s seizures, as tumor-related seizure foci are usually located in the cerebral cortex.
- Curative surgical resection was deemed potentially more harmful than beneficial due to the tumor’s deep location. The decision was made to optimize seizure medical management with short-term imaging surveillance.
- Follow-up MRI revealed decreasing mass size over time, without a new site of disease.
- The patient had fewer seizures over time and was eventually weaned off antiepileptics.
- Background:
- Angiocentric glioma is a very rare low-grade glioma (WHO grade I) typically diagnosed in young patients with seizures.
- A leading theory proposes that the absence of the EAAT2 gene leads to decreased expression of a glutamate transporter, which in turn causes glutamate accumulation and hyperexcitability of intratumoral neurons.
- The tumor is commonly found in the supratentorial cortical or subcortical parenchyma. More seldomly, the glioma can be in the basal ganglia or brainstem, with few cases reported.
- Due to its rarity and low incidence of occurring in the deep gray matter, the diagnosis of angiocentric glioma may not be considered in the differential diagnosis.
- Angiocentric glioma is difficult to differentiate from other types of low-grade glioma on imaging, so biopsy is required for diagnosis.
- Classic histopathologic features include monomorphic, bipolar, spindled cells with perivascular distribution.
- MYB-QKI rearrangement is highly specific for this diagnosis.
- Clinical Presentation:
- Patients with angiocentric glioma often present with medically refractory seizures.
- Key Diagnostic Features:
- MRI: The typical imaging appearance is a nonenhancing, T1-hypointense and T2-hyperintense, well-circumscribed lesion with mass effect on adjacent brain. Unique imaging characteristics previously described in the literature include an intrinsic hyperintense rim of the cortical gyri on T1-weighted sequences and a band of T2 hyperintensity stretching from the tumor to the ventricular wall.
- Differential Diagnoses:
- Low-grade astrocytoma: Commonly found in the cerebellum, optic pathway, and suprasellar sites. Histologic features: eosinophilic Rosenthal fibers and hyalinization of blood vessels can sometimes also be observed. MRI: cyst wall enhancement. Other radiographic features include calcification and hemorrhage.
- Ganglioglioma: Can appear anywhere in the neuraxis, but more frequently found in the supratentorial region and more commonly the temporal lobes. Histologic features: perivascular lymphocytic cuffing, Rosenthal fibers, eosinophilic granular bodies, microcysts, rich reticulin network, calcification, and glomeruloid vascular proliferation. MRI: hyperintense on T2-weighted images. It can appear with cysts or calcifications. Contrast enhancement can vary from none to solid or rim-enhancing.
- Dysembryoplastic neuroepithelial tumor: Typically located in the supratentorial region and commonly seen in the temporal lobe or frontal lobe. Histologic features: multinodular architecture with heterogeneous components resembling astrocytoma or oligodendroglioma; a characteristic hallmark is columns formed of axons surrounded by oligodendrocytelike cells oriented perpendicularly to the cortical surface where floating neurons and stellate astrocytes can be found between the columns. MRI: T1 hypointense and T2 hyperintense. Enhancement can be patchy and multifocal. Skull remodeling can also sometimes be seen due to the slow growth of the tumor.
- Ependymoma: More commonly seen in the posterior fossa but can also be found in the supratentorial brain and spinal cord. Histologic features: perivascular pseudorosettes and rod-shaped bodies near the nucleus. CT: calcification, cystic areas, hemorrhage, and heterogeneous enhancement. MRI: heterogeneous enhancement with T1 contrast; blooming can sometimes be seen on SWI.
- Treatment
- Curative treatment is surgical resection.
- However, as this case illustrates, conservative management is an option. Fortunately, over time this mass decreased in size and seizures dissipated.
