Neuropathology — MCQs

Neuropathology Indian Medical PG Practice Questions and MCQs

Question 251: What are the similar features between cerebral abscess and cerebral infarct?

A. Coagulative necrosis
B. Liquefactive necrosis (Correct Answer)
C. Heals by collagen formation
D. Always develop from emboli from other sites

Explanation: **Explanation:** The hallmark similarity between a cerebral abscess and a cerebral infarct is the pattern of tissue death: **Liquefactive Necrosis.** 1. **Why Liquefactive Necrosis?** * **Cerebral Infarct:** Unlike other solid organs that undergo coagulative necrosis during ischemia, the brain undergoes liquefactive necrosis. This is due to the high lipid content of neural tissue and the relative lack of a supportive connective tissue framework [1]. Lysosomal enzymes released by necrotic neurons and microglia rapidly digest the tissue into a liquid viscus mass [1]. * **Cerebral Abscess:** This is a localized collection of pus resulting from a pyogenic bacterial infection. The influx of neutrophils leads to the release of potent hydrolytic enzymes (proteases), which liquefy the surrounding parenchyma and cellular debris, forming an abscess cavity [2]. **Analysis of Incorrect Options:** * **A. Coagulative Necrosis:** This is characteristic of hypoxic/ischemic death in all solid organs (heart, kidney, spleen) **except** the brain. * **C. Heals by collagen formation:** The CNS lacks fibroblasts. Instead of scarring by collagen, the brain heals through **Gliosis** (proliferation of astrocytes), forming a "glial scar." [2] * **D. Emboli from other sites:** While both can be embolic (e.g., septic emboli in abscess or thromboemboli in infarct), they can also arise from local spread (sinusitis for abscess) or local thrombosis (atherosclerosis for infarct) [3]. **NEET-PG High-Yield Pearls:** * **Exception Rule:** Brain = Liquefactive necrosis (Ischemic or Infective). * **Microglial Cells:** These are the resident macrophages of the CNS; they appear as "Gitter cells" (foamy macrophages) during the cleanup phase of liquefactive necrosis. * **Stain:** Luxol Fast Blue is used to highlight myelin loss in these lesions. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1268-1269. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1275-1276. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, p. 1268.

Question 252: A metastatic carcinoma in the brain of an adult most often originates from which primary cancer?

A. Stomach
B. Ovary
C. Oral cavity
D. Lung (Correct Answer)

Explanation: **Explanation:** Brain metastases are the most common intracranial tumors in adults, occurring far more frequently than primary brain malignancies. [1] **1. Why Lung Cancer is Correct:** The **Lung** is the most common primary site for brain metastasis in both men and women, accounting for approximately **40–50%** of all cases. [1] This is due to the lung's rich vascular network and the ability of tumor cells to enter the systemic arterial circulation directly, bypassing the pulmonary filtration system. Small cell lung carcinoma (SCLC) has the highest propensity to spread to the brain, though non-small cell lung cancer (NSCLC) is more common overall. **2. Why Other Options are Incorrect:** * **Stomach & Oral Cavity:** These cancers rarely metastasize to the brain. Gastrointestinal malignancies typically spread via the portal system to the liver. * **Ovary:** Ovarian cancer primarily spreads via local seeding (peritoneal cavity) and rarely involves the central nervous system. **3. High-Yield Clinical Pearls for NEET-PG:** * **Frequency Order:** The most common primary sources for brain metastasis are: **Lung > Breast > Melanoma > Renal Cell Carcinoma (RCC) > Colon.** [1] * **Melanoma:** While lung cancer is the most common *source*, Melanoma has the highest *likelihood* (percentage-wise) of spreading to the brain if the patient has advanced disease. * **Location:** Metastases usually occur at the **grey-white matter junction** (where blood vessels narrow, trapping tumor emboli) and are often **multiple** and well-circumscribed. * **Children:** In contrast to adults, the most common source of brain metastasis in children is **Neuroblastoma.** * **Choriocarcinoma:** A high-yield fact is that Choriocarcinoma, though rare, has a very high tendency for hemorrhagic brain metastasis. [1] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1317-1318.

Question 253: Neuronophagia is seen in which of the following conditions?

A. Amoebic encephalitis
B. Poliomyelitis (Correct Answer)
C. Tuberculer meningoencephalitis
D. Cerebral malaria

Explanation: **Explanation:** **Neuronophagia** is a hallmark histopathological process where damaged or necrotic neurons are surrounded and ingested by phagocytic microglia (the resident macrophages of the CNS) [2]. This process typically occurs in response to **acute viral infections** that directly target and destroy neuronal cell bodies. **1. Why Poliomyelitis is Correct:** Poliovirus has a specific tropism for the **anterior horn cells** of the spinal cord [1]. Upon infection, the virus causes neuronal necrosis. This triggers an inflammatory response where microglia aggregate around the dying motor neurons to clear the debris, forming "microglial nodules" [2]. This classic appearance of microglia scavenging dead neurons is the definition of neuronophagia [2]. **2. Why the Other Options are Incorrect:** * **Amoebic Encephalitis:** Caused by *Naegleria fowleri*, it typically presents as a rapidly fatal primary amoebic meningoencephalitis (PAM) characterized by extensive hemorrhagic necrosis and neutrophils, rather than specific neuronophagia. * **Tubercular Meningoencephalitis:** Characterized by chronic granulomatous inflammation, caseating necrosis, and a thick gelatinous exudate at the base of the brain. It primarily affects the meninges. * **Cerebral Malaria:** Caused by *Plasmodium falciparum*, the pathology involves the sequestration of parasitized RBCs in cerebral capillaries, leading to "Durck’s granulomas" (focal areas of ischemia and microglial proliferation), but not direct viral-induced neuronophagia. **High-Yield Clinical Pearls for NEET-PG:** * **Microglial Nodules:** When neuronophagia occurs in clusters, it forms microglial nodules, a pathognomonic feature of viral encephalitides (e.g., Polio, Japanese Encephalitis, Rabies) [2]. * **Red Neurons:** The earliest morphological change in irreversible neuronal injury (ischemia) is the "Red Neuron" (pyknotic nucleus, loss of Nissl substance, and eosinophilic cytoplasm). * **Central Chromatolysis:** A regenerative change in the neuronal cell body following axonal injury, characterized by swelling and peripheral displacement of the nucleus. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 710-711. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1255-1256.

Question 254: Which of the following tumors are also called as "Ghost cell tumors"?

A. Medulloblastoma
B. Acoustic neuroma
C. Primary CNS lymphoma (Correct Answer)
D. Glioblastoma

Explanation: **Explanation:** **Primary CNS Lymphoma (PCNSL)** is referred to as a **"Ghost Cell Tumor"** primarily due to its characteristic response to corticosteroid therapy. When patients with PCNSL are treated with steroids (like dexamethasone) prior to a biopsy, the tumor cells undergo rapid apoptosis and shrinkage. On histopathology, this results in a "disappearing" effect or the presence of necrotic debris and faint cellular outlines, making the tumor difficult to diagnose—hence the name "Ghost Cell Tumor." **Analysis of Options:** * **A. Medulloblastoma:** A highly malignant primitive neuroectodermal tumor (PNET) of the cerebellum, characterized by **Homer-Wright rosettes** and small blue round cells. * **B. Acoustic Neuroma (Schwannoma):** Characterized by **Antoni A** (dense) and **Antoni B** (loose) patterns with **Verocay bodies**. It does not disappear with steroids. * **D. Glioblastoma (GBM):** The most common malignant primary brain tumor, characterized by **pseudopalisading necrosis** and microvascular proliferation. **High-Yield Facts for NEET-PG:** * **Association:** Strongly associated with **HIV/AIDS** (CD4 count <50 cells/µL) and **EBV infection** [1]. * **Histology:** Most are **Diffuse Large B-Cell Lymphomas (DLBCL)**. They show a characteristic **"perivascular cuffing"** pattern (cells circling blood vessels) [1]. * **Clinical Pearl:** Always avoid giving steroids before a suspected CNS lymphoma biopsy to prevent the "Ghost Cell" phenomenon, which can lead to a false-negative pathology report. * **Marker:** CD20 positive. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1315-1316.

Question 255: A 50-year-old woman undergoes neurosurgery for resection of a well-circumscribed intracranial neoplasm attached to the dura. The tumor compressed the underlying brain parenchyma without infiltration. Which of the following is the most likely diagnosis?

A. Arteriovenous malformation
B. Glioblastoma multiforme
C. Medulloblastoma
D. Meningioma (Correct Answer)

Explanation: ### **Explanation** **Correct Answer: D. Meningioma** **Why it is correct:** The clinical presentation describes a classic **Meningioma**. These are typically benign, slow-growing tumors that arise from the **arachnoid cap cells** of the leptomeninges. Key diagnostic features mentioned in the stem include: * **Dural Attachment:** Meningiomas are extra-axial tumors that often have a "dural tail" on imaging [1]. * **Well-circumscribed & Non-infiltrative:** Unlike primary brain malignancies, they compress the underlying brain parenchyma rather than invading it, making them surgically resectable [1], [2]. * **Demographics:** They are more common in females (due to progesterone receptors) and adults aged 40–60 [3]. **Why the other options are incorrect:** * **A. Arteriovenous malformation (AVM):** This is a vascular congenital anomaly, not a neoplasm. While it can cause intracranial hemorrhage, it does not present as a solid, dural-attached mass. * **B. Glioblastoma multiforme (GBM):** This is a highly aggressive, **intra-axial** (within the brain) tumor. It is characterized by rapid infiltration of the parenchyma, necrosis, and crossing of the midline (butterfly glioma), rather than being well-circumscribed and dural-based [4]. * **C. Medulloblastoma:** This is a primitive neuroectodermal tumor (PNET) typically found in the **cerebellum of children** [4]. It is highly malignant and occurs in the posterior fossa, not as a dural-attached mass in a 50-year-old. **NEET-PG High-Yield Pearls:** * **Histology:** Look for **Psammoma bodies** (laminated calcifications) and **whorled patterns** of spindle cells [1], [2]. * **Genetics:** Frequently associated with **NF2 gene** mutations on chromosome 22 [1]. * **Imaging:** Shows intense, uniform contrast enhancement and the "dural tail sign" on MRI. * **Receptors:** Often express **Progesterone receptors**, which may explain why they can enlarge during pregnancy [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1316-1317. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 727-728. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1317-1318. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1319-1320.

Question 256: All of the following are true about the microscopic appearance of pilocytic astrocytoma, EXCEPT:

A. Bipolar cells
B. Rosenthal fibers
C. Eosinophilic granular bodies
D. Decrease in the number of blood vessels (Correct Answer)

Explanation: ### Explanation **Pilocytic Astrocytoma (WHO Grade 1)** is the most common primary brain tumor in children, typically occurring in the cerebellum. **Why Option D is the Correct Answer:** Contrary to the option, Pilocytic Astrocytoma is characterized by **prominent vascularity**. It often exhibits **vascular endothelial proliferation** (glomeruloid bodies). While in other gliomas (like Glioblastoma) this indicates high-grade malignancy, in Pilocytic Astrocytoma, it is a benign feature and does not imply a poor prognosis. Therefore, a "decrease" in blood vessels is incorrect. **Analysis of Incorrect Options:** * **A. Bipolar cells:** These are the hallmark "piloid" (hair-like) cells. They are elongated cells with thin, hair-like bipolar processes, giving the tumor its name. * **B. Rosenthal fibers:** These are thick, elongated, eosinophilic, "corkscrew" shaped structures found within astrocytic processes. They represent degenerated intermediate filaments (ubiquitin and αB-crystallin). * **C. Eosinophilic granular bodies (EGBs):** These are small, proteinaceous droplets found in the tumor. Their presence is a classic marker of slow-growing, low-grade tumors. **NEET-PG High-Yield Pearls:** * **Biphasic Pattern:** Microscopic examination shows a mix of dense (Rosenthal fibers) and loose/microcystic (EGBs) areas. * **Genetics:** Strongly associated with **BRAF gene** alterations (KIAA1549-BRAF fusion). * **Imaging:** Classically presents as a **cystic lesion with an enhancing mural nodule** in the cerebellum. * **Prognosis:** Excellent; usually curable by surgical resection.

Question 257: Intranuclear inclusions in oligodendrocytes are seen in which of the following conditions?

A. Creutzfeldt Jakob disease
B. Polio
C. Japanese encephalitis
D. Progressive multifocal leukoencephalopathy (Correct Answer)

Explanation: ### Explanation **Progressive Multifocal Leukoencephalopathy (PML)** is the correct answer because it is caused by the reactivation of the **JC virus** (a polyomavirus) in immunocompromised patients [1]. The virus specifically infects and destroys **oligodendrocytes**, the cells responsible for myelinating the Central Nervous System. Pathologically, this leads to multifocal areas of demyelination. The hallmark microscopic finding is the presence of **ground-glass, basophilic intranuclear viral inclusions** within enlarged oligodendrocyte nuclei [1]. #### Analysis of Incorrect Options: * **Creutzfeldt-Jakob Disease (CJD):** This is a prion disease characterized by **spongiform encephalopathy** (vacuolation of the neuropil and perikaryon of neurons). It does not feature viral inclusions. * **Polio:** The poliovirus primarily targets the **lower motor neurons** in the anterior horn of the spinal cord. While it can produce intracellular changes, it does not typically present with diagnostic oligodendrocyte inclusions. * **Japanese Encephalitis:** This is a viral encephalitis affecting neurons, often involving the thalamus and basal ganglia. It is characterized by perivascular cuffing and microglial nodules, not specific oligodendrocyte inclusions. #### NEET-PG High-Yield Pearls: * **PML Triad:** Immunosuppression (often AIDS), multifocal neurological deficits, and white matter lesions on MRI (typically non-enhancing). * **Oligodendrocytes = PML:** Remember that JC virus "eats" the myelin-making cells [1]. * **Bizarre Astrocytes:** Along with oligodendrocyte inclusions, PML often shows giant, atypical astrocytes with hyperchromatic nuclei. * **Subacute Sclerosing Panencephalitis (SSPE):** Contrast PML with SSPE (Measles virus), which shows inclusions in **both** neurons (Cowdry A) and oligodendrocytes. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1280-1281.

Question 258: Which of the following is NOT true about pilocytic astrocytoma?

A. Associated with long survival.
B. Total surgical resection is often possible.
C. Commonly involves the posterior fossa.
D. Median age at presentation is more than 80 years. (Correct Answer)

Explanation: **Explanation:** Pilocytic Astrocytoma (PA) is a **WHO Grade 1** tumor, representing the most common primary brain tumor in children and adolescents [3]. **Why Option D is the correct answer:** Pilocytic astrocytomas typically present in the **first two decades of life** (median age is approximately 10–15 years) [2]. A median age of over 80 years is incorrect and clinically inconsistent with the nature of this pediatric neoplasm. In elderly patients, high-grade gliomas like Glioblastoma Multiforme (GBM) are far more common [2]. **Analysis of Incorrect Options:** * **Option A:** PA is a slow-growing, benign tumor. With appropriate management, it is associated with an **excellent prognosis** and long-term survival rates exceeding 90% over 10 years. * **Option B:** These tumors are often **well-circumscribed** and frequently cystic with a mural nodule. This distinct demarcation from surrounding brain tissue often allows for **complete surgical resection**, which can be curative. * **Option C:** The **posterior fossa (specifically the cerebellum)** is the most common site of involvement, followed by the optic pathway and the third ventricle [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Radiology:** Classic appearance is a **large cyst with a contrast-enhancing mural nodule** in the cerebellum. * **Histopathology:** Characterized by a "biphasic" pattern (dense fibrillary areas and loose microcystic areas). * **Pathognomonic finding:** **Rosenthal fibers** (thick, eosinophilic, corkscrew-shaped inclusions) and **Eosinophilic Granular Bodies (EGBs)**. * **Genetics:** Frequently associated with **BRAF gene** alterations (KIAA1549-BRAF fusion) and **Neurofibromatosis Type 1 (NF1)** [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 724-725. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1319-1320. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 725-726.

Question 259: All of the following are true about meningiomas EXCEPT:

A. Meningiomas are predominantly benign tumors of adults.
B. They arise from the meningothelial cell of the arachnoid.
C. They are attached to the pia mater. (Correct Answer)
D. They occur in association with eighth nerve schwannomas.

Explanation: **Explanation:** Meningiomas are the most common benign intracranial tumors in adults. Understanding their origin and anatomical relationship is crucial for NEET-PG. **1. Why Option C is the correct (False) statement:** Meningiomas arise from the **arachnoid cap cells** (meningothelial cells). Anatomically, they are **extra-axial** tumors that are **attached to the dura mater**, often forming a characteristic "dura tail" on imaging [1]. They compress the underlying brain parenchyma but do not originate from or primarily attach to the pia mater; instead, they are easily separated from the brain surface because they remain external to the pial barrier [1], [2]. **2. Analysis of other options:** * **Option A:** Correct. Most meningiomas are slow-growing, WHO Grade 1 benign tumors, typically presenting in the 4th to 6th decades of life. * **Option B:** Correct. The cell of origin is the meningothelial cell located in the arachnoid villi [4]. * **Option D:** Correct. There is a strong association between meningiomas and **Neurofibromatosis Type 2 (NF2)** [1], [2]. Patients with NF2 characteristically present with bilateral eighth nerve (vestibulocochlear) schwannomas and multiple meningiomas [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** Look for **Psammoma bodies** (laminated calcifications) and **whorled patterns** of cells [1], [2]. * **Genetics:** Loss of the **NF2 gene (Merlin)** on chromosome **22q** is the most common genetic alteration [1]. * **Risk Factors:** Prior radiation exposure and female gender (due to **progesterone receptors** on the tumor cells, which may cause them to enlarge during pregnancy) [1], [3]. * **Common Sites:** Parasagittal region, olfactory groove, and sphenoid wing. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1316-1317. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 727-728. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1317-1318. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1319-1320.

Question 260: Which of the following is considered a low-grade Central Nervous System tumor?

A. Diffuse astrocytoma
B. Anaplastic astrocytoma
C. Glioblastoma multiforme
D. Meningioma (Correct Answer)

Explanation: The grading of Central Nervous System (CNS) tumors follows the **WHO Classification of Tumors of the CNS**, which ranges from Grade 1 (benign, slow-growing) to Grade 4 (highly malignant). **Why Meningioma is the correct answer:** Meningiomas are primarily extra-axial tumors arising from the arachnoid cap cells. The vast majority (approx. 80-90%) are classified as **WHO Grade 1**. They are slow-growing, well-circumscribed, and often cured by surgical resection [1]. While atypical (Grade 2) and anaplastic (Grade 3) variants exist, "Meningioma" as a general entity is classically considered a low-grade tumor compared to the infiltrative gliomas listed. **Analysis of Incorrect Options:** * **Diffuse Astrocytoma (Option A):** These are **WHO Grade 2** tumors. While "low-grade" in clinical parlance compared to GBM, they are infiltrative by nature and have a high tendency to progress to higher grades, making them more aggressive than a Grade 1 Meningioma. * **Anaplastic Astrocytoma (Option B):** These are **WHO Grade 3** tumors characterized by increased cellularity, nuclear atypia, and significant mitotic activity [2]. * **Glioblastoma Multiforme (Option C):** This is the most common primary malignant brain tumor and is **WHO Grade 4**. It is characterized by necrosis and/or microvascular proliferation. **NEET-PG High-Yield Pearls:** * **Psammoma bodies:** Classically seen in Meningiomas (also seen in Papillary Thyroid CA, Serous Ovarian CA, and Mesothelioma) [1]. * **Imaging:** Meningiomas show a characteristic **"Dural Tail Sign"** on contrast-enhanced MRI. * **Genetics:** Loss of chromosome **22q** (NF2 gene) is the most common genetic alteration in meningiomas [1]. * **Pilocytic Astrocytoma:** Another high-yield **WHO Grade 1** tumor, typically found in the cerebellum of children, characterized by **Rosenthal fibers**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1316-1317. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 725-726.

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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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