General Pathology Practice Questions

Q: What is the most common site of liquefactive necrosis?

Brain. **Explanation:** **Liquefactive necrosis** is characterized by the transformation of the tissue into a liquid, viscous mass. This occurs due to the digestion of dead cells by hydrolytic enzymes. **Why the Brain is the Correct Answer:** In the Central Nervous System (CNS), ischemic injury (infarct) uniquely results in liquefactive necrosis rather than coagulative necrosis [1]. This is primarily because the brain has a **high lipid content** and **low protein framework**. Additionally, the brain is rich in lysosomal enzymes (hydrolases) and lacks a strong supporting connective tissue stroma. When cells die, these enzymes quickly digest the tissue, and the area is eventually cleared by microglia (macrophages), leaving a cystic cavity. From 10 days to 3 weeks, the tissue liquefies, eventually leaving a fluid-filled cavity [1]. **Why Other Options are Incorrect:** * **Kidney, Liver, and Spleen:** These are solid visceral organs. Ischemic injury (infarct) in these organs typically leads to **Coagulative Necrosis**. In coagulative necrosis, the basic structural outline of the tissue is preserved for several days because the injury denatures not only structural proteins but also the enzymes responsible for proteolysis. **NEET-PG High-Yield Pearls:** 1. **Two Main Scenarios for Liquefactive Necrosis:** * Ischemic injury/Infarction in the **Brain**. * **Abscess formation** (focal bacterial or fungal infections), where inflammatory cells (neutrophils) release potent enzymes that liquefy the surrounding tissue. 2. **Coagulative Necrosis** is the most common pattern of necrosis overall (except in the brain). 3. **Key Histology:** In liquefactive necrosis, the tissue architecture is completely lost [1]; in coagulative necrosis, "tombstone" appearances (preserved outlines without nuclei) are seen. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1268-1269.

Q: A diabetic male presented with seizures. Radiological examination shows a lesion. Histopathological examination shows liquefactive necrosis. What is the most important mechanism responsible for this?

Enzymatic degradation. ***Enzymatic degradation*** - Liquefactive necrosis, common in the brain (e.g., in stroke or brain abscess as suggested by the presentation in a **diabetic** patient), is defined by the complete dissolution of dead tissue into a viscous liquid mass [1]. - This dissolution is mediated by the robust release of **hydrolytic enzymes** from inflammatory cells (like **neutrophils** in an abscess) and the deceased parenchymal cells themselves, leading to the formation of a fluid-filled cavity [1]. *Mechanical* - Mechanical injury (trauma) is a *cause* of cell death and tissue damage, but it does not describe the specific biochemical process of liquefying the dead cells. - Mechanical factors primarily lead to **coagulative necrosis** initially if blood supply is compromised, or immediate cellular disruption, which is then processed by other mechanisms. *Ischemic* - Ischemia (lack of blood flow) is a common *cause* of necrosis (e.g., cerebral infarction), which often results in liquefactive necrosis in the CNS due to its high lipid content [1]. - While ischemia is the initiating event in many cases of liquefaction (especially stroke), the actual conversion of solid dead tissue into a liquid consistency requires the action of catabolic **enzymes**. *Pressure* - Pressure usually leads to generalized **atrophy** or localized **ischemia** (e.g., pressure sores or hydrocephalus), but it is not the fundamental molecular mechanism defining liquefactive necrosis. - Severe localized pressure that compromises microcirculation leads to ischemic injury, and the subsequent type of necrosis (liquefactive or coagulative) depends on the affected organ. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1268-1269.

Q: Which genetic syndrome is caused by a deletion of the short arm of chromosome 5 (5p deletion)?

Cri-du-chat syndrome. ***Cri-du-chat syndrome*** - This syndrome is classically defined by a partial terminal deletion of the short arm of chromosome 5, designated as **5p deletion**. - Key clinical features include severe **intellectual disability**, **microcephaly**, and the characteristic high-pitched, monotonic **cat-like cry** that gives the syndrome its name. *Edward syndrome* - Edward syndrome is caused by an extra copy of chromosome 18 (**Trisomy 18**) [1]. - Clinical findings are often severe, including **micrognathia**, overlapping fingers, and **rocker-bottom feet** [1]. *Patau syndrome* - Patau syndrome is caused by an extra copy of chromosome 13 (**Trisomy 13**) [1]. - It is associated with severe midline defects such as **holoprosencephaly**, **cleft lip and palate**, and **polydactyly** [1]. *Turner syndrome* - Turner syndrome is a sex chromosome abnormality resulting from the absence of one X chromosome (45,X), making it a form of **monosomy X** [2]. - It primarily affects females, causing features like **short stature**, primary **amenorrhea** due to streak ovaries, and a **webbed neck** [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 168-169. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 175-177.

Q: Which of the following is pro-apoptotic?

Bax. ***Bax*** - Bax is a key **pro-apoptotic** effector protein from the Bcl-2 family [1]. Upon activation by stress signals, it translocates to the mitochondria and forms pores in the outer membrane [2]. - This pore formation, along with Bak, leads to **Mitochondrial Outer Membrane Permeabilization (MOMP)**, which releases **cytochrome c** and initiates the intrinsic caspase cascade of apoptosis [3]. *Bcl-2* - Bcl-2 is the prototypical **anti-apoptotic** protein that prevents apoptosis by binding to and inhibiting pro-apoptotic proteins like Bax and Bak [2]. - By preventing MOMP, it maintains mitochondrial integrity and is often overexpressed in cancers, such as follicular lymphoma, contributing to cell survival [2]. *Bcl-xL* - Bcl-xL is another major **anti-apoptotic** protein in the Bcl-2 family, with a function very similar to Bcl-2 [2]. - It promotes cell survival by sequestering pro-apoptotic BH3-only proteins and preventing the activation of Bax and Bak. *Mcl-1* - Mcl-1 (Myeloid cell leukemia-1) is a critical **anti-apoptotic** protein that is essential for the survival of various cell types [2]. - Its primary role is to inhibit apoptosis by neutralizing pro-apoptotic proteins, and its high levels are often associated with tumor progression and resistance to chemotherapy [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, pp. 65-67. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 310. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, pp. 64-65.

Question 1

What is the most common site of liquefactive necrosis?

Accepted Answer

Brain

Answer

Kidney

Answer

Liver

Answer

Spleen

Question 2

Autopsy of a specimen shows pale infarction. Pale infarct is seen in all of the following organs, EXCEPT:

Accepted Answer

Lung

Answer

Heart

Answer

Spleen

Answer

Kidney

Question 3

Frozen section is/are used for all except:

Accepted Answer

Acid-fast bacilli staining

Answer

Enzyme studies

Answer

Intraoperative histopathological examination

Answer

Fat staining

Question 4

Autopsy of a specimen shows pale infarction. Pale infarct is seen in all of the following organs, EXCEPT:

Accepted Answer

Lung

Answer

Heart

Answer

Spleen

Answer

Kidney

Question 5

A 1-year-old boy presents with a delay in motor development. Progressive muscle weakness and blindness ensue, and the patient dies within a year. The brain at autopsy shows swollen neurons that contain numerous lysosomes filled with lipid. Which of the following is the most likely diagnosis?

Accepted Answer

Tay-Sachs disease

Answer

AL amyloidosis

Answer

Hurler syndrome

Answer

Phenylketonuria

Question 6

A 40-year-old female patient complains of excessive bleeding and drowsiness following a road traffic accident 5 hours ago, with a lacerated wound on the lower back region. General physical examination reveals: Blood pressure - 80/60 mmHg, Jugular venous pressure - low, Pulsus paradoxus - present, Cardiac output - Increased. The patient is in which type of shock?

Accepted Answer

Distributive

Answer

Neurogenic

Answer

Obstructive

Answer

Hypovolemic

Question 7

A diabetic male presented with seizures. Radiological examination shows a lesion. Histopathological examination shows liquefactive necrosis. What is the most important mechanism responsible for this?

Accepted Answer

Enzymatic degradation

Answer

Ischemic

Answer

Mechanical

Answer

Pressure

Question 8

Which genetic syndrome is caused by a deletion of the short arm of chromosome 5 (5p deletion)?

Accepted Answer

Cri-du-chat syndrome

Answer

Edward syndrome

Answer

Turner syndrome

Answer

Patau syndrome

Question 9

Which of the following is pro-apoptotic?

Accepted Answer

Bax

Answer

Bcl-2

Answer

Bcl-xL

Answer

Mcl-1

Question 10

Which of the following is a change seen in irreversible cell injury?

Accepted Answer

Amorphous density of mitochondria

Answer

Cellular Swelling

Answer

Bleb formation

Answer

Clumping of chromatin

General Pathology — MCQs

General Pathology — MCQs

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