Neuropathology Practice Questions

Q: Drop metastases are seen in which of the following tumors?

Medulloblastoma. **Explanation** **1. Why Medulloblastoma is Correct:** Medulloblastoma is a highly malignant primitive neuroectodermal tumor (PNET) arising from the roof of the fourth ventricle. It has a notorious propensity for **leptomeningeal carcinomatosis**, where tumor cells detach and travel via the cerebrospinal fluid (CSF) to seed distant sites. When these cells settle at the base of the spinal cord (theca), they form nodular deposits known as **"drop metastases."** MRI of the entire neuroaxis (brain and spine) is mandatory for staging because up to 30-40% of patients have spinal seeding at the time of diagnosis. **2. Analysis of Incorrect Options:** * **Ependymoma:** While ependymomas (especially the cellular subtype) can occasionally spread via CSF, it is significantly less common than in medulloblastoma. * **Cerebellar Astrocytoma:** These are typically low-grade (Pilocytic Astrocytoma), well-circumscribed, and slow-growing. They do not typically spread via the CSF. * **Neuroblastoma:** This is an extracranial tumor arising from the adrenal medulla or sympathetic chain. While it can metastasize to the bone/orbit (Proptosis), it does not cause "drop metastases" within the CNS. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common site for drop metastasis:** The lumbosacral region (due to gravity). * **Imaging Gold Standard:** Contrast-enhanced MRI of the spine ("Zuckerguss" or "icing" appearance on the cord). * **Other tumors causing drop metastases:** Germinoma (most common CNS germ cell tumor to do so), Pineoblastoma, and high-grade Gliomas. * **Medulloblastoma Classic Sign:** "Homer-Wright rosettes" on histology and a "hyperdense mass" on non-contrast CT due to high cellularity.

Q: Kernohan-Woltman sign (notch) is seen in which type of brain herniation?

Uncal herniation. **Explanation:** The **Kernohan-Woltman notch** is a classic "false localizing sign" seen in cases of severe **Uncal herniation** (Option A). **Pathophysiology:** In uncal herniation, the medial aspect of the temporal lobe (uncus) is pushed over the edge of the tentorium cerebelli. While the uncus typically compresses the ipsilateral (same side) third cranial nerve, in some cases, it displaces the entire midbrain laterally. This causes the **contralateral cerebral peduncle** to be compressed against the sharp, rigid edge of the opposite tentorial notch. Because the motor fibers (corticospinal tract) decussate in the medulla, compression of the *opposite* peduncle results in **ipsilateral hemiparesis** (weakness on the same side as the primary lesion). **Why other options are incorrect:** * **Central herniation (B):** Involves downward displacement of the diencephalon and midbrain through the tentorial notch. It typically presents with bilateral pupillary changes and progressive brainstem dysfunction rather than a focal notch sign. * **Transfalcial (Subfalcine) herniation (C):** The cingulate gyrus is pushed under the falx cerebri. This may compress the anterior cerebral artery but does not involve the tentorial notch or midbrain peduncles. * **Foraminal (Tonsillar) herniation (D):** Cerebellar tonsils are pushed through the foramen magnum, leading to medullary compression and respiratory arrest; it does not produce the Kernohan notch. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of Uncal Herniation:** Ipsilateral dilated pupil (CN III palsy), contralateral hemiparesis, and decreasing level of consciousness. * **Kernohan’s Notch Paradox:** It is a "false localizing sign" because the hemiparesis occurs on the **same side** as the mass lesion. * **Imaging:** Best visualized on MRI as an indentation on the cerebral peduncle contralateral to the herniating uncus.

Question 1

Which of the following tumors causes polycythemia due to increased erythropoietin production?

Accepted Answer

Cerebellar hemangioblastoma

Answer

Medulloblastoma

Answer

Ependymoma

Answer

Oligodendroglioma

Question 2

Drop metastases are seen in which of the following tumors?

Accepted Answer

Medulloblastoma

Answer

Ependymoma

Answer

Cerebellar astrocytoma

Answer

Neuroblastoma

Question 3

A 42-year-old man presents with worsening involuntary jerky movements, depression, and progressive dementia. He dies within several years, and autopsy reveals bilateral atrophy of the caudate nuclei. What is the basic abnormality involved in this individual's disease process?

Accepted Answer

Triple repeat mutation

Answer

Acquired enzyme deficiency

Answer

Slow virus infection

Answer

DNA repair defect

Question 4

A 42-year-old woman gives birth to a neonate with multiple congenital abnormalities including a flat facial profile, slanted eyes, epicanthal folds, Brushfield spots, short nose, short neck, dysplastic ears, clinodactyly, a large protruding tongue, and a pronounced heart murmur. As an adult, the brain of this patient will show histopathologic changes characteristic of which of the following neurologic diseases?

Accepted Answer

Alzheimer disease

Answer

Huntington disease

Answer

Krabbe disease

Answer

Multiple sclerosis

Question 5

All of the following are common sites of a berry aneurysm, EXCEPT:

Accepted Answer

Vertebral artery

Answer

Posterior cerebral artery

Answer

Anterior cerebral artery

Answer

Middle cerebral artery

Question 6

Which area of the brain most commonly undergoes atrophy in Alzheimer's disease?

Accepted Answer

Temporoparietal

Answer

Parieto-occipital

Answer

Frontoparietal

Answer

Temporo-occipital

Question 7

Which protein is primarily associated with Alzheimer's disease?

Accepted Answer

Apolipoprotein E gene

Answer

Presenilin II

Answer

Amyloid precursor protein

Answer

All of the above

Question 8

An immunocompromised person presents with a history of seizures and an MRI revealing a temporal lobe lesion. Brain biopsy results showed multinucleated giant cells with intranuclear inclusions. What is the most probable cause of the lesion?

Accepted Answer

Herpes simplex virus

Answer

Hepatitis C virus

Answer

Listeria monocytogenes

Answer

Coxsackievirus

Question 9

Kernohan-Woltman sign (notch) is seen in which type of brain herniation?

Accepted Answer

Uncal herniation

Answer

Central herniation

Answer

Transfalcial herniation

Answer

Foraminal herniation

Question 10

All of the following are true regarding primary CNS lymphoma, except:

Accepted Answer

Anaplastic large cell lymphomas are the most common histologic group.

Answer

Most primary brain lymphomas are of B-cell origin.

Answer

Hooping is characteristic of primary brain lymphoma.

Answer

Primary lymphomas of the CNS are aggressive.

Neuropathology — MCQs

Neuropathology — MCQs

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