Neuropathology Practice Questions

Q: Rosenthal fibers are characteristically seen in which of the following?

Glial fibrillary acidic protein (GFAP). **Explanation:** **Rosenthal fibers** are elongated, eosinophilic, corkscrew-shaped inclusion bodies found within the processes of astrocytes. 1. **Why Option C is Correct:** Rosenthal fibers are primarily composed of **Glial Fibrillary Acidic Protein (GFAP)**, which is the intermediate filament characteristic of astrocytes. These fibers represent a degenerative change or a chronic reactive state where GFAP, along with heat shock proteins (like αB-crystallin and HSP27) and ubiquitin, undergoes cross-linking and aggregation. 2. **Why Other Options are Incorrect:** * **Option A (Heat shock proteins):** While heat shock proteins (αB-crystallin) are *present* within Rosenthal fibers, the primary structural backbone and the defining diagnostic component is GFAP. * **Option B (Fibrillar proteins):** This is a generic term. While GFAP is a type of intermediate filament, "Fibrillar proteins" is too non-specific for a pathology exam. * **Option D (Globulins):** Globulins are plasma proteins (like immunoglobulins) and are not associated with the intracellular cytoskeletal pathology of astrocytes. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Association:** Rosenthal fibers are the hallmark of **Alexander Disease** (a leukodystrophy caused by mutations in the *GFAP* gene). * **Tumor Association:** They are most characteristically seen in **Pilocytic Astrocytoma** (WHO Grade I), typically found in the cerebellum of children. * **Other Conditions:** They can also be seen in chronic reactive gliosis (e.g., around a syrinx or a slow-growing tumor) and Craniopharyngiomas. * **Staining:** They are intensely **Eosinophilic** on H&E stain and strongly positive for **GFAP** on immunohistochemistry.

Q: Which chromosome mutation is associated with medulloblastoma?

Chromosome 17. **Explanation:** **Medulloblastoma** is the most common malignant brain tumor in children, typically arising in the cerebellum. The most characteristic cytogenetic abnormality associated with this tumor is **Isochromosome 17q (i17q)**. This mutation involves the loss of the short arm (17p) and the duplication of the long arm (17q). The loss of 17p is significant because it houses the **TP53** tumor suppressor gene (though TP53 mutations are specifically linked to the SHH subgroup), and i17q is a hallmark of the Group 3 and Group 4 molecular subtypes of medulloblastoma, carrying a poorer prognosis. **Analysis of Incorrect Options:** * **Chromosome 16:** Mutations here are more commonly associated with renal pathologies (like ADPKD - PKD1) or certain leukemias, but not classically with medulloblastoma. * **Chromosome 18:** Trisomy 18 (Edwards Syndrome) is a multisystem genetic disorder. While it increases the risk of some tumors (like Wilms tumor), it is not the primary association for medulloblastoma. * **Chromosome 19:** Codeletion of 1p/19q is the diagnostic molecular marker for **Oligodendrogliomas**, not medulloblastoma. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Always arises in the **cerebellum** (vermis in children, hemispheres in adults). * **Histology:** Characterized by **Homer-Wright Rosettes** and "small round blue cells." * **Drop Metastasis:** It has a high propensity to spread via CSF to the spinal cord [2]. * **Molecular Subgroups:** WNT (best prognosis), SHH, Group 3 (worst prognosis), and Group 4. * **Genetic Syndromes:** Associated with **Turcot Syndrome** (APC gene) and **Gorlin Syndrome** (PTCH1 gene) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 306-307. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1314-1315.

Q: Glioma of the optic nerve is usually?

Pilocytic. **Explanation:** Optic nerve gliomas are most commonly **Pilocytic Astrocytomas** (WHO Grade I). These are slow-growing, relatively benign tumors that typically occur in children and young adults [1]. **Why Pilocytic is correct:** Pilocytic astrocytomas have a predilection for the optic pathway (optic nerve, chiasm, and hypothalamus). When associated with **Neurofibromatosis Type 1 (NF1)**, they are frequently bilateral. Histologically, they are characterized by "hair-like" bipolar cells, **Rosenthal fibers** (eosinophilic corkscrew-shaped inclusions), and eosinophilic granular bodies. **Analysis of Incorrect Options:** * **Gemistocytic Astrocytoma:** This is a variant of diffuse astrocytoma (Grade 2) characterized by large, eosinophilic cell bodies with eccentric nuclei. It has a high rate of progression to glioblastoma and is not typical for the optic nerve. * **Fibrillary Astrocytoma:** This refers to the most common subtype of low-grade diffuse astrocytoma. It typically involves the cerebral hemispheres in adults [2], not the optic nerve in children. * **Lamellar:** This is not a recognized histological subtype of glioma. **High-Yield Clinical Pearls for NEET-PG:** * **Association:** 15–30% of children with NF1 develop optic pathway gliomas. * **Imaging:** Classic "fusiform" enlargement of the optic nerve on MRI. * **Histology Keyword:** Rosenthal fibers (made of GFAP and heat shock proteins). * **Prognosis:** Excellent; these are Grade I tumors and often remain stable for years [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1319-1320. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 725-726.

Q: Medulloblastoma most commonly metastasizes to which location?

Central Nervous System (CNS). **Explanation:** Medulloblastoma is a highly malignant, Grade 4 embryonal tumor arising in the cerebellum (most commonly the vermis in children) [1]. It is characterized by its tendency to spread via the **cerebrospinal fluid (CSF) pathways**, a process known as **"drop metastasis"** [1][2]. 1. **Why CNS is Correct:** Medulloblastoma is a "small round blue cell tumor" that frequently sheds cells into the subarachnoid space. These cells travel through the CSF and seed other parts of the **Central Nervous System**, particularly the spinal cord (cauda equina) [1]. This pattern of dissemination is so characteristic that imaging of the entire neuraxis (brain and spine) is mandatory for staging. 2. **Why Incorrect Options are Wrong:** * **Lung, Liver, and Spleen:** While medulloblastoma can occasionally spread outside the CNS (extracranial metastasis), this is rare (occurring in <5% of cases). When it does occur, the most common site for systemic spread is actually the **bone**, followed by lymph nodes. Spread to the lung, liver, or spleen is significantly less common than seeding within the CNS. **High-Yield Clinical Pearls for NEET-PG:** * **Homer-Wright Rosettes:** Seen in 40% of cases (pseudorosettes with a central fibrillar core). * **Molecular Subtypes:** WNT (best prognosis), SHH, Group 3 (worst prognosis), and Group 4. * **Classic Imaging Finding:** A contrast-enhancing midline mass in the fourth ventricle causing obstructive hydrocephalus. * **"Zuckerguss" (Icing):** A term used to describe the thick, white "sugar-coating" of the leptomeninges caused by metastatic tumor spread. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1314-1315. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 725-726.

Question 1

A patient with Neurofibromatosis, type 1 is at increased risk of developing which of the following malignant neoplasms?

Accepted Answer

Neurofibrosarcoma

Answer

Ganglioneuroma

Answer

Glioblastoma multiforme

Answer

Serous cystadenocarcinoma

Question 2

Rosenthal fibers are characteristically seen in which of the following?

Accepted Answer

Glial fibrillary acidic protein (GFAP)

Answer

Heat shock proteins

Answer

Fibrillar proteins

Answer

Globulins

Question 3

Target fibres are characteristically seen in a muscle biopsy of which condition?

Accepted Answer

Motor neuron disease

Answer

Dermatomyositis

Answer

Myasthenia gravis

Answer

Drug-induced myopathy

Question 4

All of the following are neuronal tumors, EXCEPT:

Accepted Answer

Ependymoma

Answer

Gangliocytoma

Answer

Ganglioglioma

Answer

Neurocytoma

Question 5

Sudden onset of massive bleeding from which organ is called apoplexy?

Accepted Answer

Brain

Answer

Kidney

Answer

Lungs

Answer

Heart

Question 6

Which chromosome mutation is associated with medulloblastoma?

Accepted Answer

Chromosome 17

Answer

Chromosome 16

Answer

Chromosome 18

Answer

Chromosome 19

Question 7

A 10-year-old girl has exhibited muscular weakness since early childhood that has not worsened. She can ambulate unassisted but does not participate in strenuous physical activities. On examination, she has 4/5 motor strength in proximal muscles and 5/5 in distal muscles. There is no muscle pain on palpation. A biopsy of the deltoid muscle is obtained, and with Gomori trichrome stain, microscopic analysis shows subsarcolemmal aggregates of rod-shaped intracytoplasmic inclusions. Laboratory studies show a normal serum creatine kinase. Which of the following is the most likely form of muscle disease she has?

Accepted Answer

Congenital myopathy

Answer

Channelopathy

Answer

Glycogen storage disease

Answer

Inflammatory myopathy

Question 8

Glioma of the optic nerve is usually?

Accepted Answer

Pilocytic

Answer

Gemistocytic

Answer

Fibrillary

Answer

Lamellar

Question 9

Which of the following is NOT a characteristic feature of Alzheimer's disease?

Accepted Answer

Only recent memory loss

Answer

Intranuclear neurofibrillary tangles (NFTs)

Answer

Amyloid plaques extracellularly

Answer

Decreased acetylcholine in Meynert's nucleus

Question 10

Medulloblastoma most commonly metastasizes to which location?

Accepted Answer

Central Nervous System (CNS)

Answer

Lung

Answer

Liver

Answer

Spleen

Neuropathology — MCQs

Neuropathology — MCQs

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