CNS Tumors — Gliomas

A 45-year-old man undergoes MRI for progressive headaches and is found to have a diffuse infiltrative tumor of the cerebral white matter with T2/FLAIR hyperintensity. Histopathology shows uniform fibrillary astrocytes with moderate nuclear pleomorphism and rare mitoses. Which WHO grade is most likely?

A 52-year-old man presents with a 3-month history of progressive headaches, morning vomiting, and recent-onset seizures. MRI brain shows a large intra-axial lesion in the left frontal lobe with heterogeneous enhancement, central necrosis, and significant peritumoral edema. Histopathology confirms WHO Grade IV glioblastoma multiforme with MGMT methylation status positive. What is the drug of choice for adjuvant chemotherapy following maximal safe surgical resection and concurrent chemoradiation?

A 35-year-old male presents with progressive headaches, focal seizures, and mild cognitive decline over 6 months. MRI brain shows a heterogeneous lesion in the left frontal lobe with mixed signal intensity, surrounding edema, and mass effect. Which investigation is most appropriate to confirm the diagnosis and grade the tumor?

Which histopathological feature best distinguishes oligodendroglioma from astrocytoma?

A 42-year-old Indian male presents with a 3-month history of progressive headaches, morning vomiting, and recent onset focal seizures. MRI brain reveals a well-demarcated, heterogeneous mass in the left frontal lobe with mixed signal intensity, significant peritumoral edema, and mass effect. On histopathology, the tumor shows a mixture of cells with varying nuclear sizes, frequent mitotic figures, and areas of necrosis. Immunohistochemistry is positive for GFAP and negative for IDH1 R132H mutation. What is the most likely diagnosis?