Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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December 9, 2021
Anaplastic Neuroepithelial Tumor
- Background:
- WHO grade III or IV neoplasms that arise from neuroepithelial tissues
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Can be astrocytic, oligodendroglial, ependymal, or mixed (as seen in this case)
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Highly infiltrative, aggressive tumors that spread rapidly and with poor prognosis
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This case is unique as histopathologic analysis demonstrates markers of both astrocytic and ependymal differentiation, therefore emphasizing the role of a correct, molecular-based diagnosis for an accurate classification and treatment.
- Clinical Presentation:
- High-grade malignant neuroepithelial tumors with histone point mutations typically occur in young teenagers.
- Cortical tumors can present with seizures, hemiparesis, cranial nerve palsies, and visual field deficits.
- Tumors obstructing CSF flow can cause acute hydrocephalus with associated nausea, vomiting, headache, and papilledema.
- Key Diagnostic Features:
- Most often located intra-axially, within the 4 cerebral lobes
- Heterogeneous, space-occupying mass with irregular margins, lobulations, and invasion of surrounding brain parenchyma
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Heterogeneous pattern of contrast enhancement, often with rim-enhancing areas of cystic necrosis
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These tumors can cause significant mass effect, herniation, and ventriculomegaly.
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Identification of histone point mutations on immunohistochemistry, specifically a mutant H3 K27M protein in this case
- Differential Diagnoses:
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Dysembryoplastic neuroepithelial tumor (DNET): Cortical-based, bubbly appearance; usually no diffusion restriction or enhancement; little or no vasogenic edema
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Ganglioglioma: Typical presentation is cortical-based cystic lesion with eccentric mural-enhancing component; usually no diffusion restriction; heterogeneous enhancement can be seen.
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Cystic ependymoma: Can be rarely supratentorial with overlapping imaging features; more common infratentorially near the fourth ventricle
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Atypical teratoid rhabdoid tumor: Rare intra-axial pediatric neoplasm most common in children <3 years of age (median age 18–22 months) with large areas of cystic/necrotic change, hemorrhage, calcification, and a predilection for the posterior fossa
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Anaplastic astrocytoma: WHO grade III; infiltrative with high mitotic activity
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Glioblastoma: WHO grade IV; highly infiltrative with central necrosis and hemorrhage
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Treatment:
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Aggressive surgical resection with adjuvant radiation therapy
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Chemotherapeutic interventions currently being investigated
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