General Pathology — MCQs

General Pathology Indian Medical PG Practice Questions and MCQs

Question 851: Which of the following produces non-caseating granulomas?

A. Histoplasmosis
B. Sarcoidosis (Correct Answer)
C. Syphilis
D. Coccidiomycoses

Explanation: ### Explanation **Correct Answer: B. Sarcoidosis** **Mechanism of Granuloma Formation:** A granuloma is a focal collection of inflammatory cells, primarily activated macrophages (epithelioid cells), surrounded by a rim of lymphocytes [2]. In **Sarcoidosis**, the granulomas are characteristically **non-caseating** (lacking central necrosis) [1]. This is a diagnosis of exclusion where a cell-mediated immune response (Th1 pathway) leads to the formation of compact, well-defined granulomas. Key histological features often seen within these granulomas include **Schumann bodies** (laminated calcium-protein concretions) and **Asteroid bodies** (stellate inclusions within giant cells). **Analysis of Incorrect Options:** * **A & D (Histoplasmosis and Coccidioidomycosis):** These are fungal infections. Fungal and mycobacterial infections typically trigger a delayed-type hypersensitivity reaction that results in **caseating granulomas** (central "cheese-like" necrosis) [3]. * **C (Syphilis):** Tertiary syphilis is characterized by the **Gumma**. While it is a type of granulomatous inflammation, it features "rubbery" necrosis rather than the classic non-caseating pattern of sarcoidosis. [2] **NEET-PG High-Yield Pearls:** * **Sarcoidosis:** Look for bilateral hilar lymphadenopathy, elevated Serum ACE levels, and hypercalcemia. [1] * **Kveim-Siltzbach Test:** Historically used for sarcoidosis (though now largely replaced by biopsy). * **Caseating Granuloma:** Think Tuberculosis (Acid-fast bacilli) or Fungal infections. [3] * **Non-caseating Granuloma:** Think Sarcoidosis, Crohn’s disease, Berylliosis, and Foreign body reactions. [2] * **Leprosy:** Tuberculoid leprosy shows non-caseating granulomas, whereas Lepromatous leprosy shows "foamy macrophages" without well-formed granulomas. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 700-701. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 198-200. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 717.

Question 852: The Feulgen reaction is used to test for which of the following?

A. mRNA
B. tRNA
C. DNA (Correct Answer)
D. rRNA

Explanation: **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.

Question 853: Which is the characteristic feature of apoptosis?

A. Nuclear pyknosis (Correct Answer)
B. Cellular shrinkage
C. Chromatin clumping
D. Intact cell membrane

Explanation: Apoptosis is a form of programmed cell death characterized by specific morphological changes [1]. While several options listed occur during apoptosis, **Nuclear Pyknosis** is considered the most characteristic and hallmark feature. 1. **Why Option A is correct:** In apoptosis, the nucleus undergoes **pyknosis** (chromatin condensation), which is the most characteristic feature [1]. This is followed by **karyorrhexis** (nuclear fragmentation). The chromatin aggregates peripherally under the nuclear membrane into dense masses of various shapes and sizes [1]. 2. **Why Option B is incorrect:** While **cellular shrinkage** occurs in apoptosis (unlike necrosis where cells swell), it is a general morphological feature and not as definitive a diagnostic hallmark as the specific nuclear changes. 3. **Why Option C is incorrect:** **Chromatin clumping** is a broad term. While it happens, the specific organized condensation into pyknotic masses is the defined pathological descriptor for apoptosis. 4. **Why Option D is incorrect:** An **intact cell membrane** is a key differentiator from necrosis (where the membrane is lost), but it is a state of the cell rather than a "characteristic feature" of the death process itself. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Detection:** The **TUNEL assay** is used to detect DNA fragmentation (internucleosomal cleavage by Ca²⁺/Mg²⁺ dependent endonucleases). * **DNA Laddering:** On electrophoresis, apoptotic DNA shows a characteristic **180–200 base pair "step-ladder" pattern**, whereas necrosis shows a "smear" pattern. * **Molecular Marker:** The presence of **Annexin V** on the outer leaflet of the plasma membrane (due to Phosphatidylserine flipping) is a marker of early apoptosis. * **Caspases:** These are cysteine proteases that serve as the "executioners" of apoptosis [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. 63-64. [2] 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 854: During lactation, what change do uterine smooth muscles undergo?

A. Hyperplasia
B. Hypertrophy
C. Involution (Correct Answer)
D. Atrophy

Explanation: **Explanation:** The correct answer is **Involution (Option C)**. **Understanding the Concept:** Involution is a physiological process involving the reduction in the size of an organ or tissue that had previously undergone enlargement. During pregnancy, the uterus undergoes massive expansion due to hormonal stimulation. Following delivery and during the period of **lactation**, the uterus must return to its non-pregnant state. This process is driven by a rapid decrease in estrogen and progesterone levels and the release of oxytocin (stimulated by breastfeeding), which causes contraction of the smooth muscle fibers [1]. At a cellular level, this involves a combination of **autophagy** and **apoptosis**, leading to a decrease in both cell size and cell number. **Why other options are incorrect:** * **Hyperplasia (A) & Hypertrophy (B):** These are the processes that occur **during pregnancy**. Hypertrophy (increase in cell size) and hyperplasia (increase in cell number) allow the uterus to expand to accommodate the fetus [2]. During lactation, the reverse occurs. * **Atrophy (D):** While atrophy also involves a decrease in cell size/number, it is typically a pathological response to loss of innervation, decreased blood supply, or aging (e.g., post-menopausal uterine changes) [3]. Involution is the specific term for this **physiological** regression post-delivery. **High-Yield NEET-PG Pearls:** * **Uterine changes in pregnancy:** A classic example of **combined** hypertrophy and hyperplasia [2]. * **Mechanism of Involution:** Primarily mediated by **autophagy** (intracellular degradation of organelles) and **apoptosis**. * **Breast changes:** During lactation, the mammary glands undergo hyperplasia; once breastfeeding stops, they also undergo **involution** [1]. * **Key Hormone:** Oxytocin, released during suckling, accelerates uterine involution by promoting myometrial contractions. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, p. 1048. [2] 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. 46-47. [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. 47-49.

Question 855: Which of the following statements regarding Down syndrome is FALSE?

A. It occurs due to meiotic non-disjunction of chromosome 21.
B. It is characterized by Trisomy 21.
C. The most common congenital heart defect (CHD) associated with it is an endocardial cushion defect.
D. It is the most common trisomy in humans. (Correct Answer)

Explanation: ### Explanation **Why Option D is the Correct Answer (The False Statement):** While Down syndrome is the most common **live-born** trisomy, it is **not** the most common trisomy in humans overall [4]. The most common trisomy occurring in human conceptions is **Trisomy 16**. However, Trisomy 16 is incompatible with life and invariably leads to early spontaneous miscarriage (first trimester) [1]. Therefore, it is never seen in live births, making Option D factually incorrect. **Analysis of Other Options:** * **Option A (True):** Approximately 95% of Down syndrome cases occur due to **meiotic non-disjunction**, primarily during maternal meiosis I [3]. This risk increases significantly with advanced maternal age (>35 years) [2]. * **Option B (True):** Down syndrome is cytogenetically defined by **Trisomy 21** (47, XX/XY +21), where an individual possesses three copies of chromosome 21 instead of the usual pair [2], [3]. * **Option C (True):** About 40% of children with Down syndrome have CHD. The most common is the **endocardial cushion defect** (Atrioventricular Septal Defect/AVSD), followed by Ventricular Septal Defect (VSD). **NEET-PG High-Yield Pearls:** * **Most common cause of Down Syndrome:** Meiotic non-disjunction (95%). * **Other causes:** Robertsonian Translocation (4%—usually involving chromosomes 14 and 21) and Mosaicism (1%) [2]. * **Dermatoglyphics:** Simian crease (single palmar crease) and increased ulnar loops. * **Associated Malignancies:** Acute Megakaryoblastic Leukemia (AMKL/M7) in children <5 years; Acute Lymphoblastic Leukemia (ALL) in children >5 years. * **Early-onset Alzheimer’s:** Seen in patients >40 years due to the APP (Amyloid Precursor Protein) gene located on chromosome 21. **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. 171-172. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 40-41. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 92-93.

Question 856: 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?

A. Obstruction of the common bile duct
B. Obstruction of the intrahepatic sinusoids
C. Thrombosis of the hepatic artery
D. Thrombosis of the hepatic vein (Correct Answer)

Explanation: **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.

Question 857: Which organ is least resistant to oxygen depletion?

A. Liver
B. Heart (Correct Answer)
C. Kidney
D. Spleen

Explanation: The susceptibility of an organ to oxygen depletion (hypoxia/ischemia) depends on its metabolic rate and its reliance on continuous aerobic respiration. [3] **Why the Heart is the Correct Answer:** The **Heart** is highly sensitive to oxygen deprivation because it has a very high metabolic demand and a high rate of oxygen extraction. Myocardial cells are strictly aerobic; they contain a high density of mitochondria and have limited glycolytic capacity. Irreversible cell injury (necrosis) in the myocardium begins within **20 to 40 minutes** of total ischemia. [1] In contrast, the brain (not listed here) is the most sensitive overall (3–5 minutes), [1] but among the given options, the heart is the least resistant. **Analysis of Incorrect Options:** * **Liver (A):** The liver has a dual blood supply (Portal vein and Hepatic artery), which provides a significant "safety net" against ischemia compared to organs with end-arterial supply. * **Kidney (C):** While the renal cortex is sensitive to hypoxia (leading to Acute Tubular Necrosis), the kidney can generally withstand ischemia for up to 60–90 minutes, making it more resistant than the heart. * **Spleen (D):** The spleen has a relatively lower metabolic rate compared to the heart and kidneys and is more resistant to brief periods of hypoxia. **NEET-PG High-Yield Pearls:** 1. **Hierarchy of Sensitivity:** Brain (most sensitive) > Heart > Kidney > Liver > Skeletal Muscle > Fibroblasts (most resistant). [1] 2. **Time to Irreversible Injury:** * Neurons: 3–5 minutes. [1] * Myocardium: 20–40 minutes. [2] * Hepatocytes: 1–2 hours. 3. **Morphological Note:** The earliest change in hypoxia is **cellular swelling** (due to failure of the Na+/K+ ATPase pump), while the first sign of irreversible injury is **membrane damage** and **mitochondrial vacuolization**. [2] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 140-142. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 548-550. [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. 55-56.

Question 858: Which of the following is a feature of apoptosis?

A. Cell is enlarged
B. Karyorrhexis
C. Plasma membrane intact (Correct Answer)
D. Enzymatic digestion

Explanation: **Explanation:** Apoptosis, or "programmed cell death," is a highly regulated pathway of cell death where the cell activates enzymes that degrade its own nuclear DNA and cytoplasmic proteins [1]. **Why the correct answer is right:** In apoptosis, the **plasma membrane remains intact**, but its structure is altered (e.g., flipping of phosphatidylserine to the outer leaflet) to signal phagocytes [1]. Because the membrane does not rupture, the cellular contents do not leak into the extracellular space, which is why apoptosis **does not elicit an inflammatory response** [1]. This is a hallmark distinction from necrosis. **Analysis of incorrect options:** * **A. Cell is enlarged:** In apoptosis, the cell **shrinks** (pyknosis) and becomes more eosinophilic. Cell enlargement (swelling) is a feature of necrosis (oncosis). * **B. Karyorrhexis:** While nuclear fragmentation occurs in both, it is the classic sequence of pyknosis → karyorrhexis → karyolysis that defines **necrosis**. In apoptosis, chromatin aggregates peripherally under the nuclear membrane before the nucleus breaks into fragments. * **D. Enzymatic digestion:** This refers to the leakage of lysosomal enzymes that digest the cell and surrounding tissue, a characteristic of **necrosis**. In apoptosis, cellular components are neatly packaged into "apoptotic bodies" for phagocytosis [1]. **NEET-PG High-Yield Pearls:** * **Gold Standard for Detection:** DNA Laddering (Step-ladder pattern on electrophoresis) due to internucleosomal cleavage by endonucleases. * **Most Characteristic Feature:** Chromatin condensation. * **Molecular Marker:** Annexin V (binds to phosphatidylserine). * **Key Caspase:** Caspase-3 is the "executioner" caspase common to both intrinsic and extrinsic pathways [1]. **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. 63-69.

Question 859: The KRAS proto-oncogene is associated with which type of cancer?

A. Colon cancer (Correct Answer)
B. Breast cancer
C. Bladder cancer
D. Melanoma

Explanation: **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.

Question 860: Which stain is used for glycogen?

A. PAS (Correct Answer)
B. Congo red
C. Prussian blue
D. Alcian blue

Explanation: **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.

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