General Pathology Practice Questions

Q: The Feulgen reaction is used to test for which of the following?

DNA. **Explanation:** The **Feulgen reaction** is a specialized histochemical staining technique used specifically for the identification and quantification of **DNA** (Deoxyribonucleic acid) within cells. **Why DNA is the correct answer:** The reaction relies on the **acid hydrolysis** of DNA using hydrochloric acid (HCl). This process removes purine bases (adenine and guanine) from the deoxyribose sugar, creating free aldehyde groups (forming apurinic acid). These aldehydes then react with **Schiff’s reagent**, resulting in a characteristic **magenta or reddish-purple** color. Because the reaction is stoichiometric (the intensity of the color is proportional to the amount of DNA), it is frequently used in flow cytometry and image analysis to measure ploidy. **Why other options are incorrect:** * **mRNA, tRNA, and rRNA (Options A, B, D):** These are forms of RNA. The Feulgen reaction is **negative for RNA** because the presence of a hydroxyl group (-OH) at the 2' position of the ribose sugar prevents the acid hydrolysis required to expose aldehyde groups. Therefore, the nucleolus (rich in rRNA) and the cytoplasm (rich in mRNA/tRNA) do not stain with Feulgen. **High-Yield Clinical Pearls for NEET-PG:** * **Specific Stain:** Feulgen is considered the most specific histochemical stain for DNA. * **Counterstain:** Fast Green is commonly used as a counterstain to provide contrast against the magenta DNA. * **RNA Stain:** To differentiate between DNA and RNA, the **Methyl Green-Pyronin (MGP) stain** is used (DNA stains green/blue-green, while RNA stains red/pink). * **Hydrolysis Step:** The critical step in the Feulgen reaction is the controlled acid hydrolysis; over-hydrolysis can lead to a false-negative result by destroying the DNA structure.

Q: A 44-year-old male presents with the sudden onset of severe right upper quadrant abdominal pain, ascites, tender hepatomegaly, and hematemesis. These symptoms are suggestive of Budd-Chiari syndrome. What is the cause of Budd-Chiari syndrome?

Thrombosis of the hepatic vein. **Explanation:** **Budd-Chiari Syndrome (BCS)** is a clinical triad of abdominal pain, ascites, and hepatomegaly caused by the obstruction of hepatic venous outflow [1]. **Why Option D is Correct:** The primary pathology in BCS is the **thrombosis of two or more major hepatic veins** or the intrahepatic/suprahepatic portion of the inferior vena cava (IVC) [1]. This obstruction leads to increased intrahepatic pressure, causing centrilobular congestion, sinusoidal dilation, and ischemic necrosis (nutmeg liver) [1]. The resulting portal hypertension manifests as ascites and esophageal varices (leading to hematemesis). **Why Incorrect Options are Wrong:** * **Option A:** Obstruction of the common bile duct leads to **obstructive jaundice** and biliary cirrhosis, not venous congestion. * **Option B:** Obstruction of the intrahepatic sinusoids is characteristic of **Sinusoidal Obstruction Syndrome (Veno-occlusive disease)**, often seen post-bone marrow transplant or after ingestion of pyrrolizidine alkaloids (Bush tea). * **Option C:** Thrombosis of the hepatic artery is rare due to the liver's dual blood supply; it typically causes liver infarction or biliary tree damage but does not present with the congestive features of BCS. **NEET-PG High-Yield Pearls:** * **Most common cause:** Polycythemia Vera (myeloproliferative neoplasms). * **Morphology:** The liver shows a **"Nutmeg liver"** appearance (centrilobular congestion) [1]. * **Sparing of the Caudate Lobe:** The caudate lobe often undergoes **compensatory hypertrophy** because it has independent venous drainage directly into the IVC. * **Classic Triad:** Abdominal pain, hepatomegaly, and ascites. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 869-870.

Q: The KRAS proto-oncogene is associated with which type of cancer?

Colon cancer. **Explanation:** **KRAS** (Kirsten Rat Sarcoma virus) is a proto-oncogene that encodes a small GTPase protein involved in the MAPK/ERK signaling pathway, which regulates cell growth and survival. When mutated, the KRAS protein remains constitutively active (locked in the GTP-bound state), leading to uncontrolled cellular proliferation. **Why Colon Cancer is Correct:** KRAS mutations are a hallmark of the **adenoma-carcinoma sequence** in colorectal cancer. They occur in approximately 40-50% of colorectal cancers, typically representing the transition from a small adenoma to a larger, more dysplastic polyp. Clinically, KRAS mutation status is a critical biomarker; tumors harboring these mutations are resistant to anti-EGFR biological therapies like **Cetuximab** and **Panitumumab**. **Analysis of Incorrect Options:** * **Breast Cancer:** Primarily associated with mutations in **BRCA1/BRCA2** (tumor suppressors) or amplification of **HER2/neu** (ERBB2). * **Bladder Cancer:** Most commonly associated with mutations in **FGFR3** or **HRAS** (specifically in low-grade papillary variants) and **TP53/RB** in high-grade invasive types. * **Melanoma:** Strongly associated with mutations in the **BRAF** gene (specifically the V600E mutation) and **NRAS**, rather than KRAS. **High-Yield Clinical Pearls for NEET-PG:** * **RAS Family:** KRAS (Colon, Lung, Pancreas), HRAS (Bladder, Kidney), NRAS (Melanoma, Hematologic malignancies). * **Pancreatic Cancer:** KRAS is the most frequently mutated oncogene here (>90% of cases) [1]. * **Mechanism:** RAS proteins have intrinsic GTPase activity which is impaired in mutations, preventing the hydrolysis of GTP to GDP. * **GAPs (GTPase Activating Proteins):** These act as "brakes" on RAS; loss of GAPs (like Neurofibromin 1 in NF1) leads to prolonged RAS activation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Pancreas, pp. 897-898.

Q: Which stain is used for glycogen?

PAS. **Explanation:** **PAS (Periodic Acid-Schiff)** [1] is the correct answer because it is the gold standard stain for identifying carbohydrates, specifically **glycogen** [1]. The mechanism involves periodic acid oxidizing the carbon-carbon bonds in sugars to form aldehydes, which then react with the Schiff reagent to produce a characteristic **magenta/bright pink** color. To confirm that the staining is specifically due to glycogen (and not mucin), a **Diastase digestion test** is performed; glycogen will disappear after treatment with diastase. **Analysis of Incorrect Options:** * **Congo red:** Used specifically for **Amyloid**. Under polarized light, it exhibits a pathognomonic **apple-green birefringence**. * **Prussian blue (Perl’s stain):** Used to detect **Ferric iron** ($Fe^{3+}$). It is essential for diagnosing conditions like hemosiderosis, hemochromatosis, or identifying sideroblasts in bone marrow. * **Alcian blue:** Used to stain **Acidic Mucopolysaccharides** (Mucin). It is frequently used to identify intestinal metaplasia (Barrett’s esophagus) where it stains goblet cells blue. **Clinical Pearls for NEET-PG:** * **PAS Positive substances:** Glycogen [1], Mucin, Basement membrane, Fungi (Candida/Histoplasma), and Alpha-1 antitrypsin globules. * **Best Fixative for Glycogen:** Alcohol-based fixatives (like **Carnoy’s fluid**) are preferred because glycogen is water-soluble. * **Trousseau Sign/Mucin:** Remember that Alcian blue is key for mucin-secreting adenocarcinomas. **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, p. 75.

Question 1

Which of the following produces non-caseating granulomas?

Accepted Answer

Sarcoidosis

Answer

Histoplasmosis

Answer

Syphilis

Answer

Coccidiomycoses

Question 2

The Feulgen reaction is used to test for which of the following?

Accepted Answer

DNA

Answer

mRNA

Answer

tRNA

Answer

rRNA

Question 3

Which is the characteristic feature of apoptosis?

Accepted Answer

Nuclear pyknosis

Answer

Cellular shrinkage

Answer

Chromatin clumping

Answer

Intact cell membrane

Question 4

During lactation, what change do uterine smooth muscles undergo?

Accepted Answer

Involution

Answer

Hyperplasia

Answer

Hypertrophy

Answer

Atrophy

Question 5

Which of the following statements regarding Down syndrome is FALSE?

Accepted Answer

It is the most common trisomy in humans.

Answer

It occurs due to meiotic non-disjunction of chromosome 21.

Answer

It is characterized by Trisomy 21.

Answer

The most common congenital heart defect (CHD) associated with it is an endocardial cushion defect.

Question 6

A 44-year-old male presents with the sudden onset of severe right upper quadrant abdominal pain, ascites, tender hepatomegaly, and hematemesis. These symptoms are suggestive of Budd-Chiari syndrome. What is the cause of Budd-Chiari syndrome?

Accepted Answer

Thrombosis of the hepatic vein

Answer

Obstruction of the common bile duct

Answer

Obstruction of the intrahepatic sinusoids

Answer

Thrombosis of the hepatic artery

Question 7

Which organ is least resistant to oxygen depletion?

Accepted Answer

Heart

Answer

Liver

Answer

Kidney

Answer

Spleen

Question 8

Which of the following is a feature of apoptosis?

Accepted Answer

Plasma membrane intact

Answer

Cell is enlarged

Answer

Karyorrhexis

Answer

Enzymatic digestion

Question 9

The KRAS proto-oncogene is associated with which type of cancer?

Accepted Answer

Colon cancer

Answer

Breast cancer

Answer

Bladder cancer

Answer

Melanoma

Question 10

Which stain is used for glycogen?

Accepted Answer

PAS

Answer

Congo red

Answer

Prussian blue

Answer

Alcian blue

General Pathology — MCQs

General Pathology — MCQs

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