Molecular Pathology Practice Questions

Q: Given below is the histopathology of liver biopsy of hemochromatosis. Which of the following stain is used to detect iron deposition?

Prussian blue stain. ***Prussian blue stain*** - **Prussian blue (Perls') stain** is the gold standard for detecting **iron/hemosiderin** in tissue sections and is essential for diagnosing hemochromatosis. - The stain works by reacting **ferric iron** with **potassium ferrocyanide** to form a characteristic **blue precipitate** that highlights iron deposits. *Alcian blue stain* - This stain is used to detect **acid mucopolysaccharides** and **mucins**, not iron deposits. - It produces a **blue color** for mucoid substances but does not react with **hemosiderin** or iron. *Crystal violet stain* - Primarily used to demonstrate **amyloid deposits** through **metachromasia** (color change from purple to pink). - Has no affinity for **iron** or **hemosiderin** and would not be useful in hemochromatosis diagnosis. *Von Kossa stain* - This stain is specifically used to detect **calcium deposits** in tissues, not iron. - It works by demonstrating **phosphates** and **carbonates** associated with calcium, producing a **black precipitate**.

Q: Liquefactive necrosis is seen in which of the following organs?

Cerebrum. **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 Cerebrum is Correct:** In the **Central Nervous System (CNS)**, hypoxic cell death (infarction) uniquely results in liquefactive necrosis [1]. This is attributed to two main factors: 1. **High Lipid Content:** The brain is rich in lipids and low in supportive connective tissue. 2. **Enzymatic Digestion:** Microglial cells (the brain's macrophages) release powerful lysosomal enzymes that rapidly digest the necrotic tissue, leaving a fluid-filled cavity [1]. **Why Other Options are Incorrect:** * **Kidney & Heart:** These solid organs typically undergo **Coagulative Necrosis** following an infarct. In this process, the basic structural outline of the tissue is preserved for several days because the injury denatures both structural proteins and enzymes, blocking proteolysis. * **Intestine:** Ischemic injury to the bowel usually leads to **Gangrenous Necrosis**. While this starts as coagulative necrosis, if a bacterial infection superimposes, it can progress to "wet gangrene" (which has a liquefactive component). However, the primary classic example for liquefactive necrosis in exams remains the brain. **High-Yield NEET-PG Pearls:** * **Exceptions:** Liquefactive necrosis is seen in two primary scenarios: **CNS Infarcts** and **Abscesses** (due to neutrophilic enzymes in pyogenic infections). * **Coagulative Necrosis** is the most common pattern of necrosis in all organs *except* the brain. * **Morphology:** The end result of liquefactive necrosis in the brain is the formation of a **cystic space** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1268-1269.

Question 1

A 22-year-old woman presents with congenital anemia requiring multiple RBC transfusions for many years. On physical examination, her skin has a bronze color and liver function tests show reduced serum albumin. Which of the following findings would most likely appear in a liver biopsy specimen?

Accepted Answer

Hemosiderin in hepatocytes

Answer

Amyloid in portal triads

Answer

Bilirubin in canaliculi

Answer

Glycogen in hepatocytes

Question 2

Mutation in the gene encoding Dystrophin is known to cause all the following except?

Accepted Answer

Hypertrophic cardiomyopathy

Answer

Duchenne muscular dystrophy

Answer

Becker muscular dystrophy

Answer

Dilated cardiomyopathy

Question 3

Given below is the histopathology of liver biopsy of hemochromatosis. Which of the following stain is used to detect iron deposition?

Accepted Answer

Prussian blue stain

Answer

Alcian blue stain

Answer

Crystal violet stain

Answer

Von Kossa stain

Question 4

Councilman bodies are formed due to which process?

Accepted Answer

Apoptosis

Answer

Necrosis

Answer

Cirrhosis

Answer

Necroptosis

Question 5

Liquefactive necrosis is seen in which of the following organs?

Accepted Answer

Cerebrum

Answer

Kidney

Answer

Heart

Answer

Intestine

Question 6

Which is the most common chromosomal anomaly seen?

Accepted Answer

Down's syndrome

Answer

Turner's syndrome

Answer

Klinefelter's syndrome

Answer

Edward's syndrome

Question 7

All of the following are methods of cellular adaptation EXCEPT?

Accepted Answer

Dysplasia

Answer

Atrophy

Answer

Hyperplasia

Answer

Hypertrophy

Question 8

Which of the following can be used as an immunohistochemical marker for juvenile rhabdomyosarcoma?

Accepted Answer

Desmin

Answer

Neurofilament

Answer

Vimentin

Answer

Cytokeratin

Question 9

Annexin V is a marker of?

Accepted Answer

Apoptosis

Answer

Necrosis

Answer

Gangrene

Answer

Aging

Question 10

Jumping genes (transposons) are primarily involved in which of the following biological processes?

Accepted Answer

Gene regulation

Answer

Chromosomal aberrations

Answer

Gene movement within a genome

Answer

Gene amplification

Molecular Pathology — MCQs

Molecular Pathology — MCQs

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