Neuropathology Practice Questions

Q: Porencephaly is most commonly due to which of the following?

Cerebral infarction. **Explanation:** **Porencephaly** refers to the presence of cystic cavities within the cerebral hemispheres that usually communicate with the ventricular system or the subarachnoid space. 1. **Why Cerebral Infarction is correct:** The primary pathophysiology of porencephaly is an **encephaloclastic process**—the destruction of previously normal brain tissue [1]. The most common cause is a **localized vascular insult or cerebral infarction** occurring during late fetal life or the early postnatal period [2]. When an area of the brain undergoes ischemic necrosis, the dead tissue is resorbed, leaving behind a fluid-filled cavity (porencephalic cyst) [2]. 2. **Why the other options are incorrect:** * **Dandy-Walker Syndrome:** This is a posterior fossa malformation characterized by agenesis/hypoplasia of the cerebellar vermis and cystic dilation of the fourth ventricle [1]. It does not typically result in cerebral hemispheric cysts. * **Fetal Alcohol Syndrome:** This leads to microcephaly, holoprosencephaly, or migration defects (like heterotopias), but is not a primary cause of porencephalic cysts. * **Trisomy 13 (Patau Syndrome):** This chromosomal anomaly is strongly associated with **holoprosencephaly** (failure of the forebrain to divide), not the destructive cystic lesions seen in porencephaly. **High-Yield Clinical Pearls for NEET-PG:** * **Schizencephaly vs. Porencephaly:** Schizencephaly is a developmental migration defect (gray matter-lined clefts) [3], whereas Porencephaly is an acquired destructive lesion (usually smooth-walled). * **Hydranencephaly:** This is the most extreme form of porencephaly, where the entire cerebral hemispheres are replaced by a thin-walled sac of CSF, usually due to bilateral internal carotid artery occlusion. * **Clinical Presentation:** Patients often present with seizures, hemiparesis, and developmental delay depending on the location of the cyst.

Q: Which of the following is not a histological feature of adamantinomatous craniopharyngioma?

Papillae lined by well-differentiated squamous epithelium. **Explanation:** Craniopharyngiomas are benign tumors arising from remnants of **Rathke’s pouch**. They exist in two distinct clinico-pathological variants: **Adamantinomatous** (common in children) and **Papillary** (common in adults). **Why Option D is the correct answer:** Option D describes the hallmark of the **Papillary Craniopharyngioma**, not the adamantinomatous type. Papillary variants lack the complex architecture of the adamantinomatous type and are characterized by solid sheets and **papillae** lined by well-differentiated, mature squamous epithelium. They notably lack "wet keratin," calcification, and stellate reticulum. **Analysis of Incorrect Options (Features of Adamantinomatous type):** * **Option A:** This variant typically shows peripheral palisading of squamous cells surrounding a loose, mesh-like center known as **stellate (spongy) reticulum**, mimicking the enamel organ of a developing tooth. * **Option B:** A pathognomonic feature is the presence of **"wet keratin"**—large, nodules of compact, lamellar keratin that often undergo secondary changes. * **Option C:** The "wet keratin" frequently undergoes **dystrophic calcification** (visible on CT scans). When keratin cells degenerate, they release **cholesterol crystals**, giving the cyst fluid a characteristic "machinery oil" appearance. **NEET-PG High-Yield Pearls:** * **Bimodal Distribution:** Peaks at 5–15 years (Adamantinomatous) and 45–60 years (Papillary). * **Imaging:** Adamantinomatous types are typically cystic and **calcified** (90%); Papillary types are usually solid/mixed and rarely calcified. * **Molecular Marker:** Adamantinomatous craniopharyngiomas are associated with **CTNNB1 (β-catenin)** mutations, while Papillary types often harbor **BRAF V600E** mutations. * **Location:** Most common suprasellar tumor in children, often causing bitemporal hemianopia and endocrine dysfunction.

Q: Degenerative changes in Huntington's chorea are seen in which brain structure?

Caudate nucleus. ### Explanation **Correct Answer: B. Caudate nucleus** **Medical Concept:** Huntington’s Disease (HD) is an **autosomal dominant** neurodegenerative disorder characterized by the expansion of **CAG trinucleotide repeats** in the *HTT* gene on chromosome 4. The hallmark pathological feature is the progressive atrophy of the **striatum**, specifically the **Caudate nucleus** [1] and the Putamen. The degeneration primarily affects **GABAergic medium spiny neurons** [2]. Loss of the caudate nucleus leads to the characteristic "boxcar ventricles" (enlargement of the frontal horns of the lateral ventricles) seen on neuroimaging [1]. This loss of inhibitory output results in the motor hyperactivity known as **chorea** [3]. **Analysis of Incorrect Options:** * **A. Cerebellum:** Primarily involved in coordination and balance. Degeneration here leads to ataxia, not chorea [1]. It is the site of pathology in Spinocerebellar Ataxias (SCAs). * **C. Red nucleus:** Located in the midbrain, it is involved in motor coordination (specifically gait). It is not the primary site of degeneration in Huntington’s. * **D. Pons:** Part of the brainstem containing nuclei for cranial nerves and respiratory centers. Atrophy of the pons is characteristic of Multiple System Atrophy (MSA-C), appearing as the "hot cross bun sign." **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** Anticipation occurs (earlier onset in successive generations), especially with **paternal transmission**. * **Triad of Symptoms:** Chorea, Dementia (Subcortical), and Psychiatric disturbances (depression/aggression). * **Neurotransmitters:** Characterized by **decreased GABA and Acetylcholine**, and **increased Dopamine** in the nigrostriatal pathway. * **Imaging:** MRI shows bilateral atrophy of the caudate heads [1]. * **Treatment:** Tetrabenazine or Deutetrabenazine (VMAT2 inhibitors) are used to manage chorea by depleting dopamine [1].

Q: What is the probable diagnosis for a cyst in a child that is located at and associated with vertebral defects?

Neuroenteric cyst. **Explanation:** The correct answer is **Neuroenteric cyst**. **1. Why Neuroenteric Cyst is correct:** A neuroenteric cyst (also known as a gastrocytoma of the spinal cord) is a rare congenital lesion resulting from the failure of the **notochordal canal** to separate from the **endoderm** (primitive foregut) during the third week of embryogenesis. This persistent connection results in a cyst lined by mucin-secreting alimentary or respiratory epithelium. Characteristically, these cysts are associated with **vertebral anomalies** (such as hemivertebrae, butterfly vertebrae, or spina bifida) because the abnormal connection interferes with the normal development of the vertebral bodies. **2. Why other options are incorrect:** * **Myelocele:** While associated with vertebral defects (spina bifida aperta), a myelocele is a form of neural tube defect where the spinal cord is exposed to the surface. It is not a "cyst" lined by epithelium but rather a failure of neural tube closure. * **Bronchogenic cyst:** These are also foregut derivatives but are typically located in the mediastinum. While they share similar histology, they are not classically associated with vertebral defects. * **Neuroblastoma:** This is a solid malignant tumor derived from neural crest cells (adrenal medulla or sympathetic chain). It is not a cystic lesion and does not typically cause congenital vertebral body malformations. **3. High-Yield Pearls for NEET-PG:** * **Location:** Most commonly found in the **cervical or upper thoracic** spine, usually intradural-extramedullary. * **Histology:** Lined by simple or pseudostratified columnar/cuboidal epithelium (often with goblet cells). * **Triad:** Think of Neuroenteric cyst when you see: **Intraspinal cyst + Vertebral defect + Foregut-derived lining.** * **Imaging:** Often presents as a well-circumscribed cyst on MRI; look for associated "split cord" or vertebral anomalies.

Q: A 45-year-old patient presented with neurological deficits and seizures. Imaging showed a lesion in the temporal lobe. Biopsy of the lesion was taken for histological examination. Based on the characteristic histological features, what is the most likely diagnosis?

Oligodendroglioma. ***Oligodendroglioma*** - Classic **"fried egg"** histological appearance with **perinuclear halos** and **"chicken wire" capillary pattern** are pathognomonic features of oligodendroglioma. - Commonly presents in **adults** with **seizures** and preferentially affects the **temporal lobe**, making it consistent with this clinical presentation. *Glioblastoma* - Shows **pseudopalisading necrosis** and **microvascular proliferation** with highly pleomorphic cells, not the uniform "fried egg" appearance. - Typically presents as a **rapidly growing** mass with **ring enhancement** on imaging, often in older patients (>50 years). *Pilocytic astrocytoma* - Characterized by **Rosenthal fibers** and **eosinophilic granular bodies** with biphasic architecture of loose and compact areas. - More common in **children and young adults**, typically located in the **cerebellum** or **optic pathway**, not temporal lobe. *Medulloblastoma* - Shows **small blue round cells** with high **mitotic activity** and **Homer Wright rosettes** in densely packed sheets. - Exclusively occurs in the **posterior fossa** (cerebellum/brainstem) and is primarily a **pediatric tumor**, not temporal lobe lesions in adults.

Question 1

Senile plaques in Alzheimer's disease are rich in which component?

Accepted Answer

Amyloid

Answer

Tau protein

Answer

Apolipoprotein E

Answer

Neuroglia

Question 2

A 60-year-old woman has a history of being treated for endometrial cancer with surgery and radiation 5 years ago. She now presents with a large necrotic tumor that follows the course of the sciatic nerve. What is the most likely diagnosis?

Accepted Answer

Malignant peripheral nerve sheath tumor

Answer

Solitary neurofibroma

Answer

Neurofibromatosis type 2

Answer

Schwannoma

Question 3

Lacunar infarcts are caused by?

Accepted Answer

Lipohyalinosis of penetrating arteries

Answer

Middle carotid artery involvement

Answer

Emboli to anterior circulation

Answer

None of the above

Question 4

Physical examination of a 14-year-old boy demonstrates six coffee-colored skin macules up to 3 cm in diameter. No other skin lesions are noted, but a small mass lesion is felt in the subcutaneous tissues below two of the macules. These masses are most likely closely associated with which of the following structures?

Accepted Answer

Peripheral nerves

Answer

Arrector pili muscles

Answer

Hair follicles

Answer

Sebaceous glands

Question 5

Porencephaly is most commonly due to which of the following?

Accepted Answer

Cerebral infarction

Answer

Dandy-Walker syndrome

Answer

Fetal alcohol syndrome

Answer

Trisomy 13

Question 6

Which of the following is not a histological feature of adamantinomatous craniopharyngioma?

Accepted Answer

Papillae lined by well-differentiated squamous epithelium

Answer

Nests and cords of squamous epithelium embedded in spongy reticulum

Answer

Compact, lamellar keratin formation ("wet keratin")

Answer

Dystrophic calcification and cholesterol crystals

Question 7

Degenerative changes in Huntington's chorea are seen in which brain structure?

Accepted Answer

Caudate nucleus

Answer

Cerebellum

Answer

Red nucleus

Answer

Pons

Question 8

What is the probable diagnosis for a cyst in a child that is located at and associated with vertebral defects?

Accepted Answer

Neuroenteric cyst

Answer

Myelocele

Answer

Bronchogenic cyst

Answer

Neuroblastoma

Question 9

A 45-year-old patient presented with neurological deficits and seizures. Imaging showed a lesion in the temporal lobe. Biopsy of the lesion was taken for histological examination. Based on the characteristic histological features, what is the most likely diagnosis?

Accepted Answer

Oligodendroglioma

Answer

Glioblastoma

Answer

Pilocytic astrocytoma

Answer

Medulloblastoma

Question 10

Neurofibrillary tangles are a deposition of which of the following substances?

Accepted Answer

Tau protein

Answer

Amyloid-beta peptide

Answer

Lewy bodies

Answer

Hirano bodies

Neuropathology — MCQs

Neuropathology — MCQs

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