Neuro-oncology (Intracranial and Spinal Tumors)
Core concepts
Know the WHO classification and grading of CNS tumors, with emphasis on the molecular markers that now define diagnosis: IDH status, 1p/19q codeletion, MGMT promoter methylation, and H3K27M mutation. Understand the imaging and clinical features of glioblastoma, lower-grade glioma, meningioma, pituitary adenoma, vestibular schwannoma, metastasis, and primary CNS lymphoma. Learn the principles of surgical resection, extent-of-resection assessment, and the roles of radiation and chemotherapy (temozolomide for glioblastoma). For spinal tumors, distinguish extradural, intradural extramedullary, and intramedullary lesions.
Traps
- Assuming grade alone determines prognosis without molecular context; IDH-mutant gliomas have better outcomes than IDH-wildtype.
- Missing that primary CNS lymphoma is typically periventricular and steroid-responsive, which can mask diagnosis if steroids are given before biopsy.
- Confusing meningioma (dural-based, enhancing, often with a dural tail) with a dural metastasis.
- Forgetting that pituitary adenomas can present with apoplexy, a surgical emergency.
Worked example / rule of thumb
An adult with a ring-enhancing necrotic hemispheric mass and surrounding edema most likely has glioblastoma; maximal safe resection followed by chemoradiation is standard. Rule of thumb for spinal tumors: pain worse at night or at rest suggests tumor; extradural lesions usually cause earlier cord compression, while intramedullary lesions produce a syrinx and dissociated sensory loss.