ABPath Neuropathology 2 — Questions and Answers
Question 1: A perivascular pseudorosette pattern on histology is MOST characteristic of which brain tumor?
- Oligodendroglioma
- Ependymoma (Correct answer)
- Choroid plexus papilloma
- Craniopharyngioma
Correct answer: Ependymoma
Ependymomas characteristically display perivascular pseudorosettes (tumor cell processes tapering toward vessels) and true ependymal rosettes.
Question 2: Which genetic alteration is PATHOGNOMONIC for oligodendroglioma per WHO 2021 CNS classification?
- EGFR amplification
- IDH mutation + 1p/19q codeletion (Correct answer)
- BRAF V600E mutation
- H3 K27M mutation
Correct answer: IDH mutation + 1p/19q codeletion
The combination of IDH mutation and 1p/19q codeletion is required for the diagnosis of oligodendroglioma by WHO 2021 molecular criteria.
Question 3: Spongiform encephalopathy with PrP-positive plaques and rapid progressive dementia is MOST consistent with which condition?
- Huntington disease
- ALS
- Creutzfeldt-Jakob disease (Correct answer)
- Multi-infarct dementia
Correct answer: Creutzfeldt-Jakob disease
Creutzfeldt-Jakob disease (CJD) is a prion disease characterized by spongiform change, astrogliosis, neuronal loss, and PrP-positive amyloid plaques.
Question 4: Which stain is BEST used to highlight amyloid plaques in Alzheimer disease on formalin-fixed paraffin-embedded brain sections?
- PAS stain
- Congo red (Correct answer)
- Prussian blue
- Luxol fast blue
Correct answer: Congo red
Congo red stain reveals amyloid deposits as red-orange material with apple-green birefringence under polarized light, used to identify amyloid plaques.
Question 5: A midline H3 K27M-mutant diffuse glioma in a pediatric patient is classified as WHO Grade how?
- Grade I
- Grade II
- Grade III
- Grade IV (Correct answer)
Correct answer: Grade IV
H3 K27-altered diffuse midline glioma is automatically classified as WHO Grade IV regardless of histologic appearance, due to its uniformly poor prognosis.
Question 6: Schwannomas characteristically occur at which location in the central nervous system?
- Frontal lobe
- Cerebellum
- Cerebellopontine angle (CN VIII) (Correct answer)
- Third ventricle
Correct answer: Cerebellopontine angle (CN VIII)
Vestibular schwannomas (acoustic neuromas) arise from the vestibulocochlear nerve sheath at the cerebellopontine angle and are the most common schwannoma location.
ABPath Neuropathology 2
A perivascular pseudorosette pattern on histology is MOST characteristic of which brain tumor?