Neuropathology Practice Questions

Q: What are Gitter cells?

Modified macrophages in the CNS. ***Modified macrophages in CNS*** - Gitter cells are **modified macrophages** that have phagocytized lipid and other debris in the central nervous system (CNS), particularly in response to injury or disease [1][2]. - They play a crucial role in **cleaning up cellular debris** and are involved in the inflammatory response within the CNS [2]. *Macroglia* - Macroglia refers to **supportive cells** in the CNS, including astrocytes and oligodendrocytes, rather than being specifically modified macrophages. - It does not specifically describe the **phagocytic role** characteristic of Gitter cells. *Oligodendrocytes* - Oligodendrocytes primarily function to **myelinate axons** in the CNS and do not possess the same phagocytic capabilities as Gitter cells. - They are involved in **insulation** of neuronal axons rather than debris clearance. *Astrocytes* - Astrocytes are the principal **supportive glial cells** in the CNS and do not exhibit the characteristics of Gitter cells. - Their functions include **maintaining blood-brain barrier**, regulating blood flow, and supporting neuronal metabolism, not phagocytosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1255-1256. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 697-698.

Q: Which receptors are blocked in Myasthenia Gravis?

ACh receptors. ***Ach receptors*** - Myasthenia Gravis is an **autoimmune disease** where **antibodies** block, alter, or destroy the **nicotinic acetylcholine receptors** at the **neuromuscular junction** [1], [2]. - This blockage prevents **acetylcholine** from binding to the receptors, leading to impaired muscle contraction and **muscle weakness** [1]. *Ca++ receptors* - **Calcium channels** (not "receptors" in this context) are involved in the release of **acetylcholine** from the presynaptic terminal, but they are not the primary target in Myasthenia Gravis [1]. - While calcium influx is crucial for neurotransmitter release, the problem in Myasthenia Gravis lies postsynaptically, at the **acetylcholine receptor** [2]. *Na+ receptors* - **Sodium channels** are essential for generating and propagating **action potentials** in muscle fibers after acetylcholine binds and opens the acetylcholine receptor. - They are not directly targeted by autoantibodies in Myasthenia Gravis; the issue occurs upstream, preventing the initial depolarization signal [2]. *Opioid receptors* - **Opioid receptors** are involved in pain modulation and other central nervous system functions, primarily binding endorphins and exogenous opioids. - They have no role in the pathophysiology of Myasthenia Gravis, which is a disorder of the **neuromuscular junction** [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 213-214. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1237-1239.

Q: Medulloblastoma arises exclusively from the cells of

Immature embryonal cells. ***Immature embryonal cells*** - **Medulloblastoma** is a malignant **embryonal tumor** of the cerebellum, exclusively arising from primitive neuroectodermal cells. - These tumors are thought to originate from remnants of the **external granular layer** of the cerebellum or other primitive neuroectodermal cells. *Ependymal cells* - Tumors arising from **ependymal cells** are called **ependymomas**, which typically occur within the ventricles of the brain or spinal cord. - Ependymomas have distinct histological features and clinical behavior compared to medulloblastomas. *Neurons* - Tumors primarily composed of neurons or with significant neuronal differentiation include **gangliogliomas** and **central neurocytomas**. - **Medulloblastomas** largely consist of undifferentiated, small round cells with minimal evidence of neuronal maturation. *Spindle-shaped cells* - **Spindle-shaped cells** are characteristic of various tumor types, including some **gliomas** (e.g., pilocytic astrocytoma) or mesenchymal tumors. - While some medulloblastoma variants can show desmoplastic features, the hallmark cell type is a small, round, blue embryonal cell.

Q: Alzheimer type II astrocytes are seen in which condition?

Hepatic encephalopathy. ***Hepatic encephalopathy*** - **Alzheimer type II astrocytes** are characteristic histological findings in cases of **hepatic encephalopathy**, reflecting the brain's response to elevated ammonia levels. - These astrocytes show enlarged, pale nuclei with prominent nucleoli and marginal chromatin, indicating cellular stress from metabolic dysfunction in the setting of liver failure. *Alzheimer's* - Alzheimer's disease is characterized by the presence of **neurofibrillary tangles** (tau protein) and **amyloid plaques** (beta-amyloid protein), not Alzheimer type II astrocytes. - Astrocytes in Alzheimer's disease may show reactive changes, but they do not typically manifest as the specific "Alzheimer type II" morphology. *Parkinsonism* - Parkinsonism is primarily characterized by the degeneration of **dopaminergic neurons** in the substantia nigra and the presence of **Lewy bodies** (alpha-synuclein aggregates). - While glial cells (astrocytes and microglia) do play a role in neuroinflammation in Parkinson's, they do not exhibit the specific Alzheimer type II astrocytic change. *Binswanger disease* - Binswanger disease is a form of **vascular dementia** characterized by diffuse white matter lesions due to chronic ischemia and damage to small cerebral blood vessels. - The pathology primarily involves demyelination and axonal loss in the white matter, with reactive gliosis, but not the specific changes seen in Alzheimer type II astrocytes.

Q: Plaques jaunes are seen in which condition?

Atherosclerosis. ***Head injury*** - **Plaques jaunes**, or yellow plaques, are primarily associated with brain injuries, particularly in areas of **contusion** or **hemorrhage** [1]. - These plaques may represent **lipid-laden macrophages** and indicate areas of *necrosis* and inflammation in the brain [1]. *Endocarditis* - Endocarditis is characterized by **vegetations** on heart valves rather than plaques in the brain. - Symptoms typically include **fever**, **murmurs**, and **embolization**, which do not involve yellow plaques. *Syphilis* - Syphilis may cause *gummatous lesions* but is not associated with yellow plaques in the brain. - Typical findings include **rash** and **ulcerative lesions**, particularly during the secondary stage. *Atherosclerosis* - Atherosclerosis involves **plaque formation** in blood vessels but these are not the same as **plaques jaunes** in neurological contexts. - It is characterized by **cholesterol** deposits and plaque rupture leading to cardiovascular events, not plaques seen in head injuries. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1262-1264.

Q: Which of the following brain tumors is considered the most aggressive and has the worst prognosis?

Glioblastoma Multiforme. ***Glioblastoma Multiforme*** - This is a **Grade IV astrocytoma** and is the most common and most aggressive primary brain tumor in adults [1]. - It is characterized by rapid growth, a highly **infiltrative nature**, and poor response to treatment, leading to a very short median survival [1]. *Meningioma* - These are typically **benign (Grade I)** tumors originating from the meninges, accounting for about one-third of all primary brain tumors [2]. - While they can cause symptoms due to mass effect, they usually have a **slow growth rate** and a good prognosis after surgical resection [2]. *Anaplastic astrocytoma* - This is a **Grade III astrocytoma**, which is malignant but generally less aggressive than glioblastoma multiforme (Grade IV) [1]. - It shows **increased cellularity**, nuclear atypia, and mitotic figures, but lacks the microvascular proliferation and necrosis characteristic of glioblastoma [1]. *Primary CNS lymphoma* - This is a **rare non-Hodgkin lymphoma** that primarily affects the brain, spinal cord, or eyes. - While aggressive, it often responds to **chemotherapy** and radiation, making its prognosis generally better than that of glioblastoma, particularly in immunocompetent patients. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1310-1311. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1316-1317.

Q: Most common site of hypertensive intraparenchymal hemorrhage in the brain?

Putamen. ***Putamen*** - The **putamen** is the most frequent site for **hypertensive intraparenchymal hemorrhages** [1] due to the presence of numerous small, thin-walled arterioles (lenticulostriate arteries) that are highly susceptible to damage from chronic hypertension [1]. - Hemorrhages in this region often cause **contralateral hemiparesis**, **hemianesthesia**, and **gaze deviation** towards the side of the lesion due to involvement of nearby motor and sensory pathways [1]. *Thalamus* - While the **thalamus** is a common site for hypertensive hemorrhages, it is less common than the putamen [1], [2]. - Thalamic hemorrhages typically cause **contralateral sensory loss**, **oculomotor dysfunction**, and sometimes **aphasia** if the dominant hemisphere is affected. *Cerebellum* - **Cerebellar hemorrhages** are less frequent than those in the basal ganglia or thalamus [1]. - Symptoms usually include **ataxia**, **nystagmus**, vomiting, and potential brainstem compression if large. *Pons* - **Pontine hemorrhages** are among the most severe and are often rapidly fatal due to damage to vital brainstem structures [1], [2]. - They typically present with **coma**, **quadriparesis**, **pinpoint pupils**, and rapid progression to respiratory arrest.

Q: What is the first cellular response observed after a sharp nerve cut?

Chromatolysis. ***Chromatolysis*** - **Chromatolysis** is the dissolution of the Nissl bodies (rough endoplasmic reticulum) in the neuron cell body following axonal injury, which is the **first observable cellular response** [1]. - This process is a preparatory step for neuronal regeneration, indicating the cell's attempt to repair the damaged axon [1]. *Polymorphic arrangement* - This term is not typically used to describe an immediate cellular response to a nerve cut; it might refer to diverse cell shapes or arrangements in different contexts but is not a recognized initial post-injury event. - The neuron's immediate response involves changes within the cell body, not a re-arrangement of its cellular structure with other cells. *Increased protein synthesis* - While increased protein synthesis does occur during neuronal repair and regeneration, it is a consequence of chromatolysis and part of a later, more sustained response, not the very first visible cellular change [1]. - **Chromatolysis precedes** and facilitates the subsequent increase in protein synthesis necessary for axonal regrowth [1]. *Macrophage activation* - **Macrophage activation** is a crucial part of the inflammatory response and debris clearance following nerve injury, but it is not the *first cellular response* of the neuron itself [2]. - Macrophages migrate to the site of injury hours to days after the initial insult, whereas chromatolysis begins within the neuron's cell body much earlier [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1254-1256. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 697-698.

Q: Homer-Wright rosette is seen in -

Neuroblastoma. ***Neuroblastoma*** - **Homer rosettes** are characteristic histopathological findings associated with neuroblastoma, indicating differentiation [1]. - This type of cancer typically occurs in **children**, primarily arising from the **adrenal glands** or sympathetic nervous system [1]. *Hepatoma* - Primarily affects the **liver** and is characterized by the presence of **hepatocytes** rather than Homer rosettes. - Typically associated with underlying **chronic liver disease** such as cirrhosis or hepatitis B/C. *Ependymoma* - Consists of cells arising from **ependymal cells** lining the ventricles of the brain and spinal cord, mainly involves **perivascular pseudorosettes**, not Homer rosettes. - Often presents with symptoms related to **increased intracranial pressure** due to obstruction. *Nephroblastoma* - Commonly known as **Wilms tumor**, it typically presents with a **palpable abdominal mass** in children and does not feature Homer rosettes. - Characterized by a triphasic histological pattern (blastemal, epithelial, and stromal components) rather than neuroblastic differentiation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 483-485.

Question 1

What are Gitter cells?

Accepted Answer

Modified macrophages in the CNS

Answer

Microglia

Answer

Astrocytic cells

Answer

Oligodendrocytic cells

Question 2

Which receptors are blocked in Myasthenia Gravis?

Accepted Answer

ACh receptors

Answer

Opioid receptors

Answer

Na+ receptors

Answer

Ca++ receptors

Question 3

Medulloblastoma arises exclusively from the cells of

Accepted Answer

Immature embryonal cells

Answer

Ependymal cells

Answer

Neurons

Answer

Spindle-shaped cells

Question 4

Alzheimer type II astrocytes are seen in which condition?

Accepted Answer

Hepatic encephalopathy

Answer

Parkinsonism

Answer

Alzheimer's

Answer

Binswanger disease

Question 5

Plaques jaunes are seen in which condition?

Accepted Answer

Atherosclerosis

Answer

Syphilis

Answer

Head injury

Answer

Endocarditis

Question 6

Which of the following brain tumors is considered the most aggressive and has the worst prognosis?

Accepted Answer

Glioblastoma Multiforme

Answer

Meningioma

Answer

Primary CNS lymphoma

Answer

Anaplastic astrocytoma

Question 7

Most common site of hypertensive intraparenchymal hemorrhage in the brain?

Accepted Answer

Putamen

Answer

Thalamus

Answer

Cerebellum

Answer

Pons

Question 8

Which of the following statements about peripheral nerve injury is false?

Accepted Answer

Neuropraxia is irreversible

Answer

Wallerian degeneration starts in axonotmesis

Answer

Neurotmesis is the most severe form of injury

Answer

Epineurium is intact in axonotmesis

Question 9

What is the first cellular response observed after a sharp nerve cut?

Accepted Answer

Chromatolysis

Answer

Polymorphic arrangement

Answer

Increased protein synthesis

Answer

Macrophage activation

Question 10

Homer-Wright rosette is seen in -

Accepted Answer

Neuroblastoma

Answer

Nephroblastoma

Answer

Hepatoma

Answer

Ependymoma

Neuropathology — MCQs

Neuropathology — MCQs

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