Neuropathology Practice Questions

Q: What is the most common primary site of origin for leptomeningeal carcinomatosis?

Breast. **Explanation:** **Leptomeningeal Carcinomatosis (LC)**, also known as neoplastic meningitis, occurs when malignant cells infiltrate the subarachnoid space and spread via the cerebrospinal fluid (CSF). **Why Breast is Correct:** Breast carcinoma is the **most common primary solid tumor** to cause leptomeningeal spread, accounting for approximately 30–40% of cases. The high incidence is attributed to the biological tendency of breast cancer cells (particularly lobular and HER2-positive subtypes) to seed the CSF via hematogenous spread or direct extension from parenchymal brain metastases [1]. **Analysis of Incorrect Options:** * **B. Thyroid:** While thyroid cancer can metastasize to the brain parenchyma (especially follicular variant), it rarely presents with primary leptomeningeal involvement. * **C. Bone:** Primary bone tumors (like Osteosarcoma) rarely metastasize to the meninges. While cancers like prostate or breast spread *to* bone, bone itself is not a common *origin* for LC. * **D. Liver:** Hepatocellular carcinoma (HCC) typically metastasizes to the lungs and bone; CNS involvement is rare and usually presents as focal parenchymal masses rather than diffuse leptomeningeal seeding. **High-Yield Clinical Pearls for NEET-PG:** * **Top 3 Primary Sources:** 1. Breast Cancer (Most common), 2. Lung Cancer (Small Cell > Non-Small Cell), 3. Melanoma [1]. * **Gold Standard Diagnosis:** CSF Cytology (shows malignant cells, elevated protein, and low glucose). * **Radiological Sign:** "Sugar coating" or linear enhancement of the sulci and cranial nerves on Gadolinium-enhanced MRI (Zuckerguss appearance). * **Common Presentation:** Multifocal neurological deficits (e.g., cranial nerve palsies combined with radiculopathy). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1317-1318.

Q: What is the commonest intramedullary spinal tumor?

Ependymoma. ### Explanation **Correct Option: C. Ependymoma** In the adult population, **Ependymoma** is the most common primary intramedullary spinal cord tumor (accounting for approximately 60% of cases). These tumors typically arise from the ependymal cells lining the central canal [1]. They are most frequently found in the **cervical region**. A specific subtype, the *Myxopapillary ependymoma*, is the most common tumor of the **filum terminale** and conus medullaris [1]. **Analysis of Incorrect Options:** * **A. Metastases:** While metastases are the most common cause of spinal malignancy overall, they are typically **extradural** (involving the vertebral bodies). Intramedullary metastases are rare, accounting for only about 1–2% of spinal cord tumors. * **B. Neurofibroma:** These are **extramedullary-intradural** tumors. They arise from the nerve roots rather than the spinal cord parenchyma itself. Along with Schwannomas, they are the most common tumors in the intradural-extramedullary compartment. * **D. None of the above:** Incorrect, as Ependymoma is the established primary intramedullary tumor. **NEET-PG High-Yield Pearls:** * **Pediatric Variation:** In children, **Astrocytomas** are the most common intramedullary tumors (whereas Ependymomas lead in adults). * **Radiology Sign:** Ependymomas are often well-circumscribed and may show the **"Cap sign"** (a rim of hemosiderin at the poles of the tumor) on MRI due to chronic hemorrhage. * **Association:** Spinal ependymomas are strongly associated with **Neurofibromatosis Type 2 (NF2)**. * **Surgical Note:** Unlike astrocytomas, ependymomas usually have a distinct cleavage plane, making surgical resection more feasible. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1312-1313.

Question 1

All of the following are true of watershed infarcts except?

Accepted Answer

Seen in subcortical white matter

Answer

Seen at the junction of major cerebral arteries

Answer

Cerebral vasospasm may cause it

Answer

Associated with hypoxic-ischemic encephalopathy

Question 2

Which area of the brain is relatively resistant to neurofibrillary tangles in Alzheimer's disease?

Accepted Answer

Lateral geniculate body

Answer

Visual association area

Answer

Entorhinal cortex

Answer

Cuneal gyrus (Area VI)/temporal lobe

Question 3

What is the most common primary site of origin for leptomeningeal carcinomatosis?

Accepted Answer

Breast

Answer

Thyroid

Answer

Bone

Answer

Liver

Question 4

What is the commonest intramedullary spinal tumor?

Accepted Answer

Ependymoma

Answer

Metastases

Answer

Neurofibroma

Answer

None of the above

Question 5

When collecting 4 serial samples from a lumbar puncture, what is the recommended use for the first sample?

Accepted Answer

Cell counts, including differential counts

Answer

Biochemical tests, such as protein and glucose

Answer

Bacterial culture and Gram staining

Answer

Mycobacterial and fungal culture and staining

Question 6

Which of the following cells is associated with ependymal cells rather than microglial cells?

Accepted Answer

Blepharoplasts

Answer

Rod cells

Answer

Gitter cells

Answer

Reservoir for HIV

Question 7

Neurologic abnormalities have been noted in about one-third of patients with AIDS. Which of the following is NOT seen in HIV involvement of the central nervous system?

Accepted Answer

Inclusion bodies

Answer

Perivascular giant cell

Answer

Vacuolar degeneration of the posterior column

Answer

Microglial nodule formation

Question 8

What is the most common tumor in the lateral hemisphere of the brain?

Accepted Answer

Astrocytoma

Answer

Meningioma

Answer

Ependymoma

Answer

Medulloblastoma

Question 9

Which of the following is typically seen in Alzheimer disease?

Accepted Answer

Neuritic plaques

Answer

Neurofibrillary tangles

Answer

Pick's protein

Answer

Amyloid angiopathy

Question 10

A 41-year-old woman presents with a 4-month history of diminished hearing. Physical examination reveals decreased hearing in the left ear, and the Weber tuning fork test lateralizes to the right ear. A head MRI shows a sharply circumscribed, 4-cm mass adjacent to the left pons extending toward the left inferior cerebellar hemisphere, with a smaller 1-cm lesion in a similar location on the right. Family screening identifies a similarly affected 38-year-old sibling. An inherited mutation involving which of the following genes is most likely to be present in this patient?

Accepted Answer

NF2

Answer

TP53

Answer

PTCH

Answer

TSC1

Neuropathology — MCQs

Neuropathology — MCQs

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