Neuro-oncology
Neuro-oncology
The exam tests tumor localization, imaging interpretation, histologic grading, and oncologic emergencies. Glioblastoma is IDH-wildtype and high grade, with ring enhancement and necrosis; IDH-mutant and 1p/19q-codeleted oligodendroglioma has a better prognosis. Brain metastases are the most common adult brain tumors and often occur at the gray-white junction. CNS lymphoma can mimic glioma or infection and may shrink with steroids, so biopsy should not be delayed unnecessarily. Meningiomas are extra-axial and dural-based. Emergencies include raised ICP, seizures, spinal cord compression, and tumor hemorrhage.
Worked example
A 60-year-old has seizures and a ring-enhancing frontal lesion with surrounding edema. Reasoning: consider metastasis, glioblastoma, abscess, and lymphoma. Obtain MRI with contrast and biopsy or resection based on accessibility; do not assume abscess without infection clues.
Traps
Do not give steroids before biopsy if lymphoma is possible unless needed for life-threatening edema; do not use seizure prophylaxis routinely in brain tumors without seizures; do not confuse pseudoprogression with true progression; do not miss spinal cord compression in back pain with cancer.