Oncology · Primary Brain Tumors
The facts most likely to be tested
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Glioblastoma is the most common primary malignant brain tumor in adults, typically arising in the cerebral hemispheres.
Histopathology reveals pseudopalisading necrosis and endothelial cell proliferation surrounding areas of tumor cell density.
Imaging characteristically demonstrates a ring-enhancing lesion with significant peritumoral edema and a midline shift.
Tumors frequently cross the corpus callosum, resulting in the classic butterfly glioma appearance on MRI.
The tumor is derived from astrocytes and is classified as a WHO grade 4 astrocytoma.
Patients commonly present with new-onset seizures, focal neurologic deficits, or signs of increased intracranial pressure such as morning headaches and vomiting.
Standard of care involves surgical resection followed by adjuvant radiation and temozolomide chemotherapy.
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A 62-year-old male presents to the emergency department after a first-time generalized tonic-clonic seizure. His wife reports he has had two weeks of progressive personality changes, morning headaches, and nausea. On physical exam, he has left-sided hemiparesis and papilledema. An MRI of the brain shows a large, heterogeneously enhancing mass in the right frontal lobe that crosses the midline through the corpus callosum.
What is the most likely diagnosis?
Glioblastoma
The presentation of a new-onset seizure in an older adult combined with the classic 'butterfly' appearance of a midline-crossing, ring-enhancing mass is pathognomonic for glioblastoma.
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Etiology / Epidemiology
Most common primary malignant brain tumor in adults; peak incidence 50-70 years. Associated with ionizing radiation exposure.
Clinical Manifestations
Progressive focal neurologic deficits, new-onset seizures, and signs of increased intracranial pressure (e.g., morning headaches).
Diagnosis
MRI with gadolinium contrast is the gold standard; shows butterfly glioma with ring-enhancing lesions.
Treatment
Surgical maximal safe resection followed by temozolomide and radiation therapy.
Prognosis
Highly aggressive with a median survival of 12-15 months despite aggressive therapy.
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Epidemiology & Etiology
Glioblastoma (GBM) is a WHO grade 4 astrocytoma, representing the most frequent primary brain malignancy in adults. While most cases are sporadic, rare associations exist with Li-Fraumeni syndrome and prior cranial radiation.
Pertinent Anatomy
Tumors typically arise in the cerebral hemispheres, frequently crossing the corpus callosum to involve both frontal lobes. This midline crossing is a hallmark feature of the butterfly glioma appearance.
Pathophysiology
GBM arises from astrocyte precursors, characterized by rapid cellular proliferation and neovascularization. The tumor exhibits extensive peritumoral edema due to disruption of the blood-brain barrier, leading to mass effect and midline shift.
Clinical Manifestations
Patients present with progressive focal deficits (e.g., hemiparesis, aphasia) and new-onset seizures in adults. Increased intracranial pressure manifests as morning headaches, nausea, and papilledema. Altered mental status or personality changes are common due to frontal lobe involvement.
Diagnosis
MRI with gadolinium contrast is the diagnostic study of choice, revealing irregular ring-enhancing masses with central necrosis. A stereotactic brain biopsy or surgical resection is required for definitive histopathological diagnosis, showing pseudopalisading necrosis and endothelial proliferation.
Treatment
Initial management involves maximal safe resection to reduce mass effect and obtain tissue. Post-operative standard of care is temozolomide combined with fractionated radiotherapy. Corticosteroids (e.g., dexamethasone) are essential for managing vasogenic edema.
Prognosis
Despite multimodal therapy, recurrence is nearly universal. Seizures and venous thromboembolism are frequent complications requiring prophylactic management. Median survival remains poor at 12-15 months.
Differential Diagnosis
Brain Metastasis: usually multiple lesions at the gray-white junction
Meningioma: dural-based, well-circumscribed, psammoma bodies
Primary CNS Lymphoma: common in immunocompromised, periventricular
Abscess: ring-enhancing but with restricted diffusion on MRI
Low-grade Astrocytoma: slower progression, non-enhancing