Neuropathology Practice Questions

Q: Which of the following is a pathognomonic feature of Alzheimer's disease?

Plaques and tangles. ***Plaques and tangles*** - The presence of **amyloid plaques** (extracellular deposits of beta-amyloid protein) and **neurofibrillary tangles** (intracellular aggregates of hyperphosphorylated tau protein) are the defining neuropathological hallmarks of Alzheimer's disease [1]. These are considered **pathognomonic** features upon post-mortem examination. - While other neurological conditions can have some tauopathy or amyloid deposition, the specific combination, distribution, and extensive nature of these two pathologies are unique to Alzheimer's [1]. [3] *Presence of Lewy bodies* - **Lewy bodies** are abnormal aggregates of alpha-synuclein protein that are characteristic of **Parkinson's disease** and **Lewy body dementia** [3]. - Their presence indicates a distinct neurodegenerative process, separate from Alzheimer's disease. *Presence of Pick bodies* - **Pick bodies** are cytoplasmic inclusions composed primarily of tau protein, but they are characteristic of **Pick's disease**, a type of frontotemporal dementia [2]. - Pick's disease has a different clinical presentation and neuropathological profile than Alzheimer's disease [2]. *Red neuronal degeneration (general feature)* - **Red neuronal degeneration** refers to the morphological changes seen in neurons undergoing acute irreversible ischemic injury, such as during a **stroke**. - It is a general feature of acute neuronal death and is not specific to, nor a pathognomonic feature of, Alzheimer's disease. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1292-1294. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1294-1295. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 721-722.

Q: Which nerve biopsy is taken to diagnose neuritic leprosy?

Radial cutaneous nerve. ***Radial cutaneous nerve*** - The **radial cutaneous nerve** (superficial branch of radial nerve) is the **preferred nerve for biopsy** in suspected neuritic leprosy - It is a **purely sensory nerve** with minimal functional consequences if damaged, making it the safest choice for diagnostic biopsy - This nerve is **superficially located** at the wrist and easily accessible for biopsy procedures - Provides excellent diagnostic yield as it is commonly involved in leprosy neuritis *Ulnar nerve* - While the ulnar nerve is frequently **thickened and tender** in leprosy and can be easily palpated, it is **NOT preferred for biopsy** [1] - Contains both **motor and sensory fibers**, so biopsy carries significant risk of functional impairment including weakness of intrinsic hand muscles - Clinical examination and nerve thickening is sufficient for diagnosis; biopsy is avoided due to morbidity risk *Median nerve* - The median nerve can be affected in leprosy but is **not suitable for biopsy** due to its critical motor and sensory functions - Biopsy would risk severe hand dysfunction including loss of thumb opposition and sensory loss in the lateral palm - Deep location also makes it less accessible compared to superficial cutaneous nerves *Radial nerve* - The **main radial nerve trunk** is a mixed nerve with important motor functions (wrist and finger extension) - Its deep location and functional importance make it **unsuitable for diagnostic biopsy** - Risk of wrist drop and significant morbidity makes this an inappropriate biopsy site **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 386.

Q: Which mutation is characteristic of oligodendroglioma?

1p19q codeletion. ***1p19q codeletion*** - The **codeletion of chromosomal arms 1p and 19q** is a molecular hallmark of oligodendroglioma and is crucial for diagnosis according to WHO classification [1]. - This specific genetic alteration is associated with **better prognosis** and increased responsiveness to chemotherapy and radiation in patients with oligodendroglioma. *BRAF V600E* - The **BRAF V600E mutation** is commonly found in **pleomorphic xanthoastrocytoma (PXA)** and **ganglioglioma**, but not typically in oligodendroglioma. - It is also characteristic of other cancers like **melanoma** and some **thyroid cancers**. *IDH1 mutation alone* - While an **IDH1 mutation** is present in most oligodendrogliomas, it is usually accompanied by the **1p19q codeletion** [1]. Isolated IDH1 mutation without 1p19q codeletion suggests other diffuse gliomas, such as astrocytoma. - An isolated IDH1 mutation is more characteristic of **IDH-mutant astrocytoma**, especially when 1p19q is intact. *EGFR amplification* - **EGFR amplification** is a classic genetic alteration found in **glioblastoma (GBM)**, a highly aggressive primary brain tumor [2]. - It is rarely seen in oligodendrogliomas and is associated with a **worse prognosis** in GBM. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1311-1312. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1308-1310.

Q: What is the primary pathological mechanism in classical Guillain-Barré syndrome affecting the peripheral nervous system?

It causes demyelination of peripheral nerves.. ***It causes demyelination of peripheral nerves.*** - Classical Guillain-Barré syndrome (AIDP - Acute Inflammatory Demyelinating Polyneuropathy) is an autoimmune disorder where the immune system attacks the **myelin sheath** surrounding peripheral nerves. - This **demyelination** impairs nerve signal conduction, leading to weakness and paralysis. - AIDP represents the most common form of GBS in Western countries (~85-90% of cases). *It blocks neurotransmitter release.* - Conditions like **Lambert-Eaton myasthenic syndrome** primarily involve antibodies targeting presynaptic voltage-gated calcium channels, thereby reducing neurotransmitter release. - While GBS affects nerve conduction, its primary mechanism is not the blockage of neurotransmitter release at the synapse. *It inhibits muscle contraction.* - Inhibition of muscle contraction is a downstream effect of impaired nerve innervation, but the fundamental problem in GBS is with the **nerve itself**, not the muscle's ability to contract directly. - Conditions like **myasthenia gravis** directly affect neuromuscular transmission by blocking acetylcholine receptors on muscle fibers. *It leads to axonal degeneration.* - While **axonal variants** of GBS exist (AMAN - Acute Motor Axonal Neuropathy; AMSAN - Acute Motor-Sensory Axonal Neuropathy), particularly common in Asia, the **classical and most common form** is characterized by **primary demyelination** (AIDP). - Pure axonal degeneration as a primary pathology is seen in specific GBS variants, not the classical presentation. - Secondary axonal damage can occur in severe or prolonged cases.

Q: In which type of cells are Negri bodies, characteristic of rabies virus infection, most commonly found?

Neurons. ***Neurons*** - **Negri bodies** are eosinophilic, sharply demarcated **intracytoplasmic inclusions** found in the cytoplasm of neurons, particularly in the **hippocampus** (Ammon's horn) and **Purkinje cells** of the cerebellum [1]. - Their presence is **pathognomonic** for **rabies virus infection**, indicating viral replication within these nerve cells [1]. *Hepatocytes* - Hepatocytes are liver cells and are not the primary site for rabies virus replication or the formation of Negri bodies. - While some viruses infect hepatocytes, rabies primarily targets the **central nervous system**. *Epithelial cells* - Epithelial cells form linings and coverings throughout the body, but they are not the primary host cells for rabies virus replication. - Rabies virus directly impacts the **nervous system**, not epithelial tissues. *Cardiomyocytes* - Cardiomyocytes are muscle cells of the heart and are not typically infected by the rabies virus. - Rabies is a **neurotropic virus**, meaning it specifically targets neuronal tissue. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1279-1280.

Q: Which of the following is a pathological characteristic of Alzheimer's disease?

Plaques and tangles. ***Plaques and tangles*** - The hallmark pathological features of **Alzheimer's disease** are extracellular **amyloid-beta plaques** and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein [1], [2]. - These accumulations lead to neuronal dysfunction and death, causing the characteristic symptoms of the disease [1]. *Increased reflexes* - **Increased reflexes** (hyperreflexia) are not a characteristic pathological feature of Alzheimer's disease; they are more commonly seen in conditions affecting upper motor neurons, such as **stroke** or **multiple sclerosis**. - Alzheimer's primarily affects cognitive function and does not typically present with significant motor system abnormalities in its early stages. *Gradual cognitive decline* - **Gradual cognitive decline** is a *clinical symptom* of Alzheimer's disease, not a pathological characteristic [1]. - It describes the functional manifestation of the underlying neuropathology rather than the specific tissue changes. *Subcortical atrophy* - Alzheimer's disease predominantly causes **cortical atrophy**, particularly affecting the hippocampus, temporal lobes, and parietal lobes, rather than primarily subcortical structures [2]. - While brain atrophy occurs, the most characteristic and specific pathological changes at the microscopic level are the **plaques and tangles**, which are the definitive diagnostic features on histopathology [1], [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1292-1294. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 720-722.

Q: A 70-year-old male presents with progressive memory loss, visual hallucinations, and parkinsonism. Which neuropathological finding is most characteristic of his condition?

Lewy Bodies. ***Lewy Bodies*** [1] - The presence of **visual hallucinations**, **memory loss**, and **parkinsonism** points towards Lewy body dementia, which is characterized by the presence of these abnormal aggregates [1]. - **Lewy bodies** contain the protein **alpha-synuclein**, which is linked to the pathophysiology of both Parkinson's disease and dementia with Lewy bodies [1][2]. *Neurofibrillary Tangles* - Typically associated with **Alzheimer's disease**, they represent **tau protein** abnormalities rather than the symptoms presented. - Do not account for the **visual hallucinations** or the combination of symptoms seen in this patient. *Pick Bodies* - Associated with **Frontotemporal lobar degeneration**, these are not related to the **parkinsonian features** or hallucinations described. - Characterized by changes in personality and social behavior, which differ from the clinical picture here. *Amyloid Plaques* - Primarily found in **Alzheimer's disease**, which does not typically present with visual hallucinations or parkinsonism. - Amyloid plaques are related to cognitive impairment, but not the combination of symptoms in this case. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1297-1298. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1296-1297.

Q: A 60-year-old man presents with memory loss, difficulty performing daily activities, and visuospatial disorientation. Which protein accumulation is characteristic of the most likely diagnosis?

Beta-amyloid. ***Beta-amyloid*** - The symptoms of memory loss, difficulty performing daily activities, and visuospatial disorientation are highly suggestive of **Alzheimer's disease**. [1] - **Beta-amyloid plaques** (extracellular) and **neurofibrillary tangles** (intracellular tau) are the two hallmark pathological features of Alzheimer's disease. [1], [2] - Beta-amyloid accumulation is considered the most **characteristic** finding, as it is relatively specific to Alzheimer's disease, whereas tau pathology can occur in various neurodegenerative conditions. [1] *Tau protein* - While **hyperphosphorylated tau protein** forms **neurofibrillary tangles**, which are equally important in Alzheimer's disease pathology, tau accumulation is **less specific** as it occurs in multiple tauopathies. [1] - Other tauopathies include frontotemporal dementia, progressive supranuclear palsy, and corticobasal degeneration, which present with different clinical profiles. - Both amyloid and tau pathology contribute to neurodegeneration in Alzheimer's disease. *Alpha-synuclein protein* - Accumulation of **alpha-synuclein protein** is characteristic of **Parkinson's disease** and **Lewy body dementia** (LBD). [2] - LBD commonly involves fluctuating cognition, visual hallucinations, and Parkinsonism, which differ from the typical Alzheimer's presentation. *Prion proteins* - **Prion diseases** (e.g., Creutzfeldt-Jakob disease) are characterized by misfolded **prion proteins**, leading to rapidly progressive dementia. - The clinical presentation typically involves a much more rapid decline (weeks to months) and additional neurological signs such as myoclonus and ataxia. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1290-1294. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 719-722.

Question 1

Which of the following is a pathognomonic feature of Alzheimer's disease?

Accepted Answer

Plaques and tangles

Answer

Presence of Lewy bodies

Answer

Presence of Pick bodies

Answer

Red neuronal degeneration

Question 2

Which nerve biopsy is taken to diagnose neuritic leprosy?

Accepted Answer

Radial cutaneous nerve

Answer

Median nerve

Answer

Radial nerve

Answer

Ulnar nerve

Question 3

Which mutation is characteristic of oligodendroglioma?

Accepted Answer

1p19q codeletion

Answer

BRAF V600E

Answer

IDH1 mutation alone

Answer

EGFR amplification

Question 4

What is the primary pathological mechanism in classical Guillain-Barré syndrome affecting the peripheral nervous system?

Accepted Answer

It causes demyelination of peripheral nerves.

Answer

It blocks neurotransmitter release.

Answer

It inhibits muscle contraction.

Answer

It leads to axonal degeneration.

Question 5

In which type of cells are Negri bodies, characteristic of rabies virus infection, most commonly found?

Accepted Answer

Neurons

Answer

Hepatocytes

Answer

Epithelial cells

Answer

Cardiomyocytes

Question 6

Which of the following is a pathological characteristic of Alzheimer's disease?

Accepted Answer

Plaques and tangles

Answer

Gradual cognitive decline

Answer

Increased reflexes

Answer

Subcortical atrophy

Question 7

A 70-year-old male presents with progressive memory loss, visual hallucinations, and parkinsonism. Which neuropathological finding is most characteristic of his condition?

Accepted Answer

Lewy Bodies

Answer

Neurofibrillary Tangles

Answer

Amyloid Plaques

Answer

Pick Bodies

Question 8

A 60-year-old man presents with memory loss, difficulty performing daily activities, and visuospatial disorientation. Which protein accumulation is characteristic of the most likely diagnosis?

Accepted Answer

Beta-amyloid

Answer

Tau protein

Answer

Alpha-synuclein protein

Answer

Prion proteins

Question 9

Which of the following best describes the pathophysiology of migraine?

Accepted Answer

Migraines involve vasodilation and neurogenic inflammation.

Answer

Migraines result from purely vascular constriction without neurogenic involvement.

Answer

Migraines are caused by cortical spreading depression alone without vascular changes.

Answer

Migraines are caused by primary vasoconstriction leading to cerebral ischemia.

Question 10

Which of the following statements is MOST accurate regarding Huntington's disease?

Accepted Answer

It is caused by an increased number of CAG repeats in the HTT gene.

Answer

There is a loss of function type of mutation

Answer

It is an autosomal recessive

Answer

It is a trinucleotide repeat expansion type of disorder

Neuropathology — MCQs

Neuropathology — MCQs

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