Neuropathology Practice Questions

Q: A 40-year-old wom an presents with headache and undergoes evaluation for a brain tumor/ cerebellopontine angle. Histopathological examination reveals a tumor composed of Antoni A and Antoni B areas. Which of the following is the most sensitive immunohistochemical marker for this tumor?

S-100 protein. ***S-100 protein*** - S-100 is a protein expressed in cells of neural crest origin, and it serves as a highly **sensitive immunohistochemical marker** for **Schwannomas**. - The tumor described presents characteristic **Antoni A** (dense, hypercellular) and **Antoni B** (loose, hypocellular) areas, which are pathognomonic for Schwannoma. *Glial fibrillary acidic protein (GFAP)* - GFAP is an intermediate filament protein primarily found in **glial cells** like astrocytes and ependymal cells. - It is used to diagnose **gliomas** (e.g., astrocytoma, ependymoma) rather than nerve sheath tumors. *Epithelial membrane antigen (EMA)* - EMA is typically positive in **meningiomas**, which also frequently occur in the cerebellopontine angle. - While it is a useful marker in neuropathology, it is not the primary diagnostic marker for a Schwannoma. *c-KIT* - c-KIT (CD117) is the standard diagnostic marker for **gastrointestinal stromal tumors (GIST)**. - It is not a useful marker for tumors originating from Schwann cells or other neural sheath components.

Q: An 8-year-old boy presents with freckling in the armpits, soft skin tumors over the back, and learning difficulties. His father has similar skin lesions. The images show findings under slit lamp. What is the most likely diagnosis?

Neurofibromatosis type 1 (NF1). ***Neurofibromatosis type 1 (NF1)*** - Characterized by diagnostic criteria including **axillary freckling (Crowe sign)** and multiple **neurofibromas**, which are soft, flesh-colored peripheral nerve sheath tumors. - The slit lamp examination in individuals with NF1 typically reveals **Lisch nodules** (iris hamartomas), which are pathognomonic for this condition. *Neurofibromatosis type 2 (NF2)* - Manifests primarily with **bilateral vestibular schwannomas**, leading to hearing loss and tinnitus, rather than the cutaneous features described. - It is less commonly associated with the specific combination of axillary freckling and neurofibromas seen in type 1. *Tuberous sclerosis complex* - Presents with **angiofibromas**, ash-leaf spots (hypopigmented macules), and **shagreen patches** instead of neurofibromas. - Commonly associated with neurological manifestations like **seizures** and intellectual disability rather than the classic NF1 signs. *Sturge-Weber syndrome* - Identified by a **port-wine stain (nevus flammeus)** in the distribution of the ophthalmic branch of the trigeminal nerve. - Associated with **leptomeningeal angiomas**, which often cause seizures and glaucoma, distinct from the neurocutaneous tumors of NF1.

Q: Which CNS tumor is typically associated with calcification?

Oligodendroglioma. **Explanation:** **Oligodendroglioma** is the correct answer because it is the most common CNS tumor to exhibit calcification, occurring in approximately **70–90% of cases**. These tumors typically arise in the frontal lobes of adults. On CT scans, the calcification often appears in a "clumped" or "punctate" pattern. Histologically, these tumors are characterized by a "fried-egg appearance" (perinuclear halos) and a "chicken-wire" vascular pattern. **Analysis of Incorrect Options:** * **Astrocytoma:** While some high-grade astrocytomas or specific subtypes (like Pilocytic Astrocytoma) may show occasional calcification (approx. 10–20%), it is not a hallmark feature compared to Oligodendroglioma. * **Medulloblastoma:** This is a highly cellular primitive neuroectodermal tumor (PNET) typically found in the posterior fossa of children. It rarely shows calcification and is better known for "Homer-Wright rosettes" and rapid CSF spread. * **Pheochromocytoma:** This is a catecholamine-secreting tumor of the adrenal medulla, not a primary CNS tumor. While it may be part of syndromes like Von Hippel-Lindau (which involves CNS hemangioblastomas), it is anatomically and pathologically irrelevant to primary CNS calcification. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Calcified CNS Lesions:** "Old Men Play Cricket" (**O**ligodendroglioma, **M**eningioma, **P**apillary Craniopharyngioma, **C**hordoma). * **Genetic Marker:** 1p/19q co-deletion is pathognomonic for Oligodendroglioma and indicates a better prognosis and response to chemotherapy. * **Craniopharyngioma:** In the pediatric population, this is the most common suprasellar tumor to show calcification (90% of cases).

Q: Which of the following tumors is characterized histologically by pseudopalisading, necrosis, endoneural proliferation, hypercellularity, and atypical nuclei?

Glioblastoma multiforme. **Explanation:** The correct answer is **Glioblastoma Multiforme (GBM)**. GBM is a Grade IV astrocytoma and the most common primary malignant brain tumor in adults [1]. **Why GBM is correct:** The histological hallmarks of GBM are defined by the "Great Five" features mentioned in the question: 1. **Pseudopalisading Necrosis:** This is the most diagnostic feature [1]. It consists of irregular zones of necrosis surrounded by "palisading" (lining up) of tumor cells. 2. **Microvascular (Endothelial) Proliferation:** Tumor cells secrete VEGF, leading to a "glomeruloid" appearance of blood vessels [1]. 3. **Hypercellularity, Pleomorphism, and Brisk Mitosis:** Reflecting its highly aggressive nature [1]. **Why other options are incorrect:** * **Schwannoma:** Characterized by **Verocay bodies** (Antoni A areas) where nuclei palisade around fibrillary processes, but it lacks necrosis and malignancy markers. * **Medulloblastoma:** A primitive neuroectodermal tumor (PNET) showing **Homer-Wright rosettes** and small round blue cells, typically found in the cerebellum of children. * **Oligodendroglioma:** Classically shows a **"fried-egg" appearance** (perinuclear halos) and a **"chicken-wire"** capillary pattern. It is associated with 1p/19q co-deletion. **High-Yield Clinical Pearls for NEET-PG:** * **Imaging:** GBM typically shows a **"Ring-enhancing lesion"** on MRI and often crosses the midline via the corpus callosum (**Butterfly Glioma**) [1]. * **Molecular Marker:** **IDH-mutation status** is now used to classify these; IDH-wildtype carries a worse prognosis. * **Location:** Most commonly found in the cerebral hemispheres. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1310-1311.

Question 1

A 40-year-old wom an presents with headache and undergoes evaluation for a brain tumor/ cerebellopontine angle. Histopathological examination reveals a tumor composed of Antoni A and Antoni B areas. Which of the following is the most sensitive immunohistochemical marker for this tumor?

Accepted Answer

S-100 protein

Answer

Glial fibrillary acidic protein (GFAP)

Answer

Epithelial membrane antigen (EMA)

Answer

c-KIT

Question 2

An 8-year-old boy presents with freckling in the armpits, soft skin tumors over the back, and
learning difficulties. His father has similar skin lesions. The images show findings under slit lamp.
What is the most likely diagnosis?

Accepted Answer

Neurofibromatosis type 1 (NF1)

Answer

Neurofibromatosis type 2 (NF2)

Answer

Tuberous sclerosis complex

Answer

Sturge-Weber syndrome

Question 3

Which CNS tumor is typically associated with calcification?

Accepted Answer

Oligodendroglioma

Answer

Astrocytoma

Answer

Medulloblastoma

Answer

Pheochromocytoma

Question 4

A 15-year-old boy complains of right-sided weakness and gait impairment. A CT scan shows a large, non-enhancing cyst in the posterior cranial fossa, with an enhancing tumor nodule in the left cerebellum. What is the most likely diagnosis?

Accepted Answer

A cystic astrocytoma

Answer

An arachnoid cyst

Answer

Rathke's cleft cyst

Answer

Glioblastoma multiforme

Question 5

Which of the following are pathological hallmarks of Alzheimer's disease?

Accepted Answer

Extracellular Beta Amyloid Plaques

Answer

Intercellular Lewy Bodies

Answer

Intracellular Pick's Bodies

Answer

Extracellular Neurofibrillary Tangles

Question 6

All of the following are true about medulloblastoma except?

Accepted Answer

The most common site is the cerebellum.

Answer

It is the most common primary malignant brain tumor in childhood.

Answer

Isochromosome 17q indicates poor prognosis.

Answer

The tumor is highly radiosensitive.

Question 7

In Alzheimer's disease, which of the following locations has the most common lesions?

Accepted Answer

Nucleus of Meynert

Answer

Amygdala

Answer

Pineal gland

Answer

Prefrontal sulcus

Question 8

All of the following are true about Berry aneurysm except:

Accepted Answer

Surgical clipping is preferred over endovascular coil occlusion

Answer

Most common type of intracranial aneurysm

Answer

Most common site is anterior communicating artery-anterior cerebral junction

Answer

Rupture of aneurysm usually occurs at the apex or dome

Question 9

Which of the following tumors is characterized histologically by pseudopalisading, necrosis, endoneural proliferation, hypercellularity, and atypical nuclei?

Accepted Answer

Glioblastoma multiforme

Answer

Schwannoma

Answer

Medulloblastoma

Answer

Oligodendroglioma

Question 10

A 33-year-old male presented with homonymous hemianopia, ataxia, and personality changes. Characteristic inclusions are seen in oligodendrocytes. What is the most probable diagnosis in this patient?

Accepted Answer

Progressive multifocal leukoencephalopathy

Answer

Creutzfeldt-Jakob disease

Answer

Japanese encephalitis

Answer

Poliomyelitis

Neuropathology — MCQs

Neuropathology — MCQs

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