Neuropathology — MCQs

An elderly man has become progressively unable to live independently over the past several years, requiring assistance with daily activities. He has no motor or sensory deficits on physical examination, but is unable to give the current date or state his location. At autopsy, a large superficial left parietal lobe hemorrhage is found, along with numerous neocortical neuritic plaques and neurofibrillary tangles in the brain. Which mechanism is most likely responsible for his disease?

Q370

Rosenthal fibers are?

Neuropathology Indian Medical PG Practice Questions and MCQs

Question 361: Absence of lymph nodes is characteristic of which type of cancer?

A. Liver
B. Lung
C. Placenta
D. Brain (Correct Answer)

Explanation: ***Brain*** - The brain lacks conventional **lymphatic drainage** vessels and **lymph nodes**, making metastasis to regional lymph nodes impossible [1]. - Due to the **blood-brain barrier** and unique immunological environment, brain tumors typically spread via cerebrospinal fluid or direct invasion rather than lymphatic routes [1]. *Liver* - The **liver** has an extensive lymphatic system with numerous **intrahepatic** and **extrahepatic lymph nodes** that can be involved in metastatic spread. - Hepatic malignancies, both primary and secondary, frequently metastasize to regional lymph nodes, such as the **hilar** and **periportal nodes**. *Lung* - The **lungs** are richly supplied with lymphatic vessels and contain a vast network of **bronchopulmonary**, **hilar**, and **mediastinal lymph nodes** [2]. - Lung cancers commonly metastasize to these regional lymph nodes, which is a critical factor in **staging** and treatment planning. *Placenta* - The **placenta** is a highly vascular organ but lacks an intrinsic lymphatic system and associated lymph nodes. - While it can be affected by gestational trophoblastic disease (a type of cancer), its metastatic spread occurs predominantly via **hematogenous routes**, not lymphatic. **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] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 724-725.

Question 362: Durck's granuloma is primarily associated with which of the following?

A. Spleen
B. Brain (Correct Answer)
C. Lymph node
D. Skull

Explanation: ***Brain*** - **Durck's granulomas** are microglial nodules specifically found in the **brain tissue** of patients with **typhoid fever**. [1] - They are a characteristic neuropathological finding associated with **S. typhi** infection. [1] *Spleen* - The spleen is a common organ affected by bacterial infections like **typhoid fever**, leading to **splenomegaly** and sometimes splenic abscesses. - However, **Durck's granulomas** are not found in the spleen; they are specific to brain lesions in typhoid. *Lymph node* - **Lymph nodes** can show reactive changes and hyperplasia in many systemic infections, including typhoid fever. - While lymphadenopathy might be present, **Durck's granulomas** are not a feature of typhoid infection in lymph nodes. *Skull* - The **skull** is the bony protection for the brain and is not directly involved in the formation of **Durck's granulomas**. - These granulomas are microscopic lesions within the brain parenchyma, not within the skull itself. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1281-1282.

Question 363: Which of the following tests is used in the evaluation of a suspected cerebrospinal fluid leak?

A. Beta-2 microglobulin
B. Beta-2 transferrin (Correct Answer)
C. Transthyretin
D. Thyroglobulin

Explanation: ***Beta-2 transferrin*** - This is the **gold standard biochemical marker** for detecting the presence of **cerebrospinal fluid (CSF)** in nasal or ear discharge. - **Beta-2 transferrin** is a desialylated isoform of transferrin that is highly specific to CSF and is not found in other bodily fluids like mucus or tears in significant quantities. *Beta-2 microglobulin* - **Beta-2 microglobulin** is a protein found on the surface of most nucleated cells and is elevated in various inflammatory conditions, some cancers, and kidney disease. - It is **not specific to CSF** and therefore not used for diagnosing CSF leaks. *Transthyretin* - **Transthyretin**, also known as prealbumin, is a transport protein for thyroid hormones and retinol. - It is a marker of **nutritional status** and its levels can be affected by liver disease or inflammation, but it is **not used for CSF leak detection**. *Tyroglobulin* - **Thyroglobulin** is a protein produced by the thyroid gland and is primarily used as a tumor marker for **differentiated thyroid cancer**. - It has **no relevance** to the diagnosis or evaluation of cerebrospinal fluid leaks.

Question 364: In which clinicopathologic category of amyloidosis is the deposition of protein 'Aβ (amyloid beta)' primarily observed?

A. Hemodialysis associated
B. Senile cerebral (Correct Answer)
C. Familial mediterranean fever
D. Systemic senile

Explanation: ***Senile cerebral*** - **Amyloid-beta (Aβ)** deposition is the hallmark of **Alzheimer's disease** and is found in the brains of individuals with **senile cerebral amyloidosis**. - Aβ plaques accumulate primarily in the **cerebral cortex** and **vessel walls**, contributing to neurodegeneration. *Familial mediterranean fever* - This is an **autoinflammatory disorder** associated with deposition of **AA amyloid** (amyloid A protein). - It leads to **systemic amyloidosis**, affecting organs like the kidneys, rather than cerebral Aβ deposition. *Hemodialysis associated* - This type of amyloidosis is caused by the deposition of **β2-microglobulin** due to its inadequate clearance in patients undergoing long-term hemodialysis. - It primarily affects the **musculoskeletal system**, including joints and tendons, not the brain. *Systemic senile* - **Systemic senile amyloidosis** is characterized by the deposition of **transthyretin (TTR)**, primarily affecting the heart and other organs. - While it occurs in older individuals (senile), it does not involve Aβ deposition in the brain.

Question 365: Rosenthal fibres are seen in which of the following tumours?

A. Pilocytic astrocytoma (Correct Answer)
B. Glioblastoma
C. Medulloblastoma
D. Ependymoma

Explanation: ***Pilocytic astrocytoma*** - **Rosenthal fibres** are highly characteristic histological findings in pilocytic astrocytomas, appearing as thick, elongated, corkscrew-shaped eosinophilic aggregates. - These are typically **well-circumscribed** tumors, most commonly found in the cerebellum of children and young adults. *Glioblastoma* - Characterized by **necrosis with pseudopalisading cells** and **microvascular proliferation**, not Rosenthal fibres. - It is a highly aggressive, grade IV astrocytoma with a poor prognosis. *Ependymoma (characterized by perivascular rosettes)* - Histologically, ependymomas are known for forming **perivascular pseudorosettes**, where tumor cells arrange around blood vessels. - These tumors arise from ependymal cells lining the ventricles and spinal cord, and do not contain Rosenthal fibres. *Medulloblastoma* - Medulloblastomas are highly malignant embryonic tumors typically found in the **cerebellum**, characterized by **small, round blue cells** and often forming Homer Wright rosettes. - They are not associated with Rosenthal fibres.

Question 366: Which of the following is NOT a typical pathologic feature of the brain in AIDS?

A. Microglial nodules
B. Perivascular giant cell invasion
C. Temporal lobe infarction (Correct Answer)
D. Vasculitis

Explanation: ***Temporal lobe infarction*** - While infarction can occur due to various causes, **temporal lobe infarction** is not a typical or primary neuropathologic feature directly associated with HIV infection itself. - HIV-related neurological complications more commonly involve widespread inflammation, opportunistic infections, or direct neurotoxic effects, rather than focal ischemic events in the temporal lobe [1]. *Perivascular giant cell invasion* - This is a **hallmark feature of HIV encephalitis (HIVE)**, characterized by the presence of multinucleated giant cells derived from macrophages/microglia, often surrounding blood vessels [1]. - These cells are infected with HIV and contribute to the inflammatory and destructive processes in the brain, representing one of the classic pathologic findings [1]. *Microglial nodules* - **Microglial nodules** are aggregations of activated microglia and macrophages, often found within the brain parenchyma in HIV-infected individuals. - They represent a **typical inflammatory response** to HIV infection and are a characteristic feature of HIV encephalitis along with multinucleated giant cells and white matter changes. *Vasculitis* - HIV infection can occasionally cause CNS vasculitis, leading to inflammation of blood vessels in the brain. - While recognized as a potential complication, it is relatively uncommon compared to the classic triad of microglial nodules, multinucleated giant cells, and white matter pathology that define typical HIV neuropathology. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 711-712.

Question 367: All of the following hereditary conditions predispose to central nervous system tumors, except.

A. Neurofibromatosis 1 & 2
B. Von-Hippel-Lindau syndrome
C. Xeroderma pigmentosum (Correct Answer)
D. Tuberous sclerosis

Explanation: ***Xeroderma pigmentosum*** - This condition primarily predisposes individuals to **skin cancers** due to defects in DNA repair mechanisms, rather than to central nervous system tumors. - **Neurological complications** can occur, but they are not associated with an increased risk of CNS tumors. *Neurofibromatosis 1 & 2* - Both types are well known for a strong association with **central nervous system tumors** [2][3], particularly **gliomas** and **meningiomas**. - Neurofibromatosis type 1 is especially linked with **optic pathway gliomas**, observable in pediatric patients. *Von-Hippel-Lindau syndrome* - This syndrome is associated with **hemangioblastomas** in the CNS [2][4], particularly in the **cerebellum** and **spinal cord** [4]. - Also predisposes to other tumors, including **renal cell carcinoma** and pancreatic neuroendocrine tumors. *Tuberous sclerosis* - Patients often develop **subependymal giant cell astrocytomas** and other brain tumors due to this condition [1][2]. - Additionally, it can lead to the formation of **hamartomas** in various organs, including the brain [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1318-1319. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 724-725. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1319-1320. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 726-727.

Question 368: Brain space-occupying lesions cause death by.

A. Brain herniation (Correct Answer)
B. Cushing's reflex
C. Decreased cerebral perfusion
D. Cerebral edema

Explanation: ***Brain herniation*** - **Brain herniation** is the ultimate cause of death in patients with space-occupying lesions because it directly compresses vital brainstem structures responsible for cardiorespiratory function [2]. - Herniation syndromes (uncal, central, tonsillar) compress the brainstem, leading to irreversible damage to autonomic regulatory centers and cardiorespiratory arrest [1], [2]. *Cushing's reflex* - **Cushing's reflex** (hypertension, bradycardia, irregular respirations) is a physiological response to increased intracranial pressure (ICP) [3]. - It is a compensatory mechanism to maintain cerebral perfusion, not the direct cause of death. - Death occurs when this protective mechanism fails and herniation supervenes [1]. *Decreased cerebral perfusion* - **Decreased cerebral perfusion** results from increased ICP exceeding cerebral perfusion pressure [3]. - While severe hypoperfusion causes brain ischemia, the immediate lethal event is **brain herniation** compressing vital brainstem structures [2]. *Cerebral edema* - **Cerebral edema** (vasogenic or cytotoxic) is a pathological consequence of space-occupying lesions that contributes to increased ICP [2]. - However, edema itself does not directly cause death; rather, it increases mass effect leading to herniation, which is the terminal event [4]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 699-700. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1257-1258. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 698-699. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1275-1276.

Question 369: An elderly man has become progressively unable to live independently over the past several years, requiring assistance with daily activities. He has no motor or sensory deficits on physical examination, but is unable to give the current date or state his location. At autopsy, a large superficial left parietal lobe hemorrhage is found, along with numerous neocortical neuritic plaques and neurofibrillary tangles in the brain. Which mechanism is most likely responsible for his disease?

A. Conformational change in the prion protein (PrP)
B. Dopamine deficiency
C. Expansion of polyglutamine repeats
D. Aggregation of Aβ peptide (Correct Answer)

Explanation: ***Aggregation of Ab peptide*** - The presence of **neocortical neuritic plaques** containing **Aβ (Amyloid beta) peptides** is indicative of Alzheimer's disease, where peptide aggregation is a crucial mechanism [1,2]. - This aggregation leads to **neurodegeneration** and associated symptoms, aligning with the patient's cognitive decline and sudden coma [2]. *Dopamine deficiency* - Primarily associated with **Parkinson's disease**, which typically presents with **motor deficits** such as tremors and rigidity, unlike this patient's purely cognitive symptoms. - Dopamine deficiency does not explain the findings of **neurosenile plaques** and **tangles** in the context of an 86-year-old male. *Conformational change in the prion protein (PrP)* - This mechanism relates primarily to **prion diseases** like Creutzfeldt-Jakob disease, characterized by rapid neurological decline and distinctive histopathological findings. - There is no evidence of **prion-like degeneration** or **spongiform changes** noted in this patient's brain autopsy findings. *Expansion of polyglutamine repeats* - This is primarily associated with **Huntington's disease**, marked by **chorea and cognitive decline**, rooted in basal ganglia dysfunction, which is not applicable here. - The findings in this patient relate more to **Alzheimer's disease** pathology than polyglutamine expansion disorders. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 721-722. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1290-1294.

Question 370: Rosenthal fibers are?

A. Present extracellularly
B. Part of cell membrane
C. Intracytoplasmic inclusions (Correct Answer)
D. Intranuclear inclusions

Explanation: **Intracytoplasmic inclusions** - **Rosenthal fibers** are characteristic **intracytoplasmic inclusions** found in **astrocytes**. - They are composed of **glial fibrillary acidic protein (GFAP)** and **alpha B-crystallin**, indicating reactive astrocytosis. *Intraclear inclusions* - **Intranuclear inclusions** are found within the **nucleus**, distinct from the cytoplasm where Rosenthal fibers are located. - Examples include viral inclusions (e.g., **CMV**) or certain neurodegenerative diseases (e.g., **Huntington's disease**), which have different compositions. *Present extracellularly* - **Extracellular components** are found outside cells and include structures like collagen or amyloid plaques. - Rosenthal fibers are **cellular components**, specifically within the cytoplasm of astrocytes, not in the extracellular space. *Part of cell membrane* - The **cell membrane** is the boundary of the cell, composed of lipids and proteins. - Rosenthal fibers are **intracellular structures** involved in the cytoskeleton and stress response, not integral parts of the cell membrane itself.

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Cellular Pathology of the Nervous System

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Cerebrovascular Diseases

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Trauma to the Central Nervous System

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Infections of the Nervous System

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Demyelinating Diseases

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Neurodegenerative Diseases

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CNS Tumors

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Peripheral Nerve Disorders

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Neuromuscular Junction Diseases

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Congenital and Developmental Disorders

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