General Pathology — MCQs

General Pathology Indian Medical PG Practice Questions and MCQs

Question 1081: Which of the following is an antiapoptotic gene?

A. Bax
B. Bad
C. Bcl-XL (Correct Answer)
D. Bid

Explanation: The regulation of apoptosis (programmed cell death) is primarily governed by the **Bcl-2 family of proteins**, which act as a rheostat to determine cell survival [1]. These proteins are categorized into two functional groups: **Pro-apoptotic** (promote death) and **Anti-apoptotic** (promote survival) [3]. ### **Explanation of the Correct Answer** **C. Bcl-XL** is the correct answer because it belongs to the **Anti-apoptotic** group of the Bcl-2 family. These proteins (including Bcl-2, Bcl-XL, and MCL-1) reside in the outer mitochondrial membrane [1]. They function by preventing the leakage of Cytochrome C into the cytosol [1]. They do this by binding to and neutralizing pro-apoptotic proteins, thereby maintaining mitochondrial membrane integrity and preventing the activation of the caspase cascade. ### **Explanation of Incorrect Options** * **A, B, and D (Bax, Bad, Bid):** These are all **Pro-apoptotic** proteins. * **Bax and Bak:** Known as "pro-apoptotic effectors," they form pores in the mitochondrial membrane (MOMP - Mitochondrial Outer Membrane Permeabilization), allowing Cytochrome C to escape [1]. * **Bad and Bid:** These belong to the "BH3-only" subset [3]. They act as sensors of cell stress and either activate Bax/Bak or inhibit anti-apoptotic proteins like Bcl-XL. ### **High-Yield Clinical Pearls for NEET-PG** * **The "Pro-Survival" Mnemonic:** Remember **Bcl-2, Bcl-XL, and MCL-1** as the "Life-savers." * **The "Pro-Death" Mnemonic:** Most others with "B" and "a" (B**a**x, B**a**k, B**a**d, B**a**m, Bik) promote **a**poptosis. * **Follicular Lymphoma Connection:** A classic pathology correlation is the **t(14;18) translocation**, which leads to the overexpression of the **Bcl-2** gene, making B-cells resistant to apoptosis and leading to malignancy [2]. * **Executioner Caspases:** Regardless of the pathway, the final "execution" of apoptosis is carried out by **Caspases 3, 6, and 7** [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 310. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 310-311. [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. 64-67.

Question 1082: Which cells of the human body are most sensitive to ischemia?

A. Neurons (Correct Answer)
B. Nephrons
C. Cardiac myocytes
D. Hepatocytes

Explanation: **Explanation:** The sensitivity of a cell to ischemia (hypoxia) is directly proportional to its metabolic rate and its dependence on aerobic respiration [1], [4]. **1. Why Neurons are the Correct Answer:** Neurons are the most metabolically active cells in the body [2]. They have a very high oxygen consumption rate and minimal glycogen stores, making them almost entirely dependent on a continuous supply of glucose and oxygen [2], [4]. Irreversible cell injury occurs in neurons within just **3 to 5 minutes** of total ischemia [1]. Within the brain, the most sensitive areas are the **Pyramidal cells of the Hippocampus (Sommer sector)** and **Purkinje cells of the Cerebellum**. **2. Analysis of Incorrect Options:** * **Cardiac Myocytes:** These are also highly sensitive but more resilient than neurons [3]. Irreversible injury (infarction) typically occurs after **20 to 30 minutes** of ischemia [1]. * **Nephrons (Renal Tubular Epithelial Cells):** These cells are sensitive to ischemia (leading to Acute Tubular Necrosis), but they can survive for approximately **2 to 3 hours** before irreversible damage sets in [4]. * **Hepatocytes:** Liver cells have a dual blood supply (portal vein and hepatic artery) and significant glycogen stores, making them relatively resistant to ischemia compared to the brain, heart, or kidneys. **3. NEET-PG High-Yield Pearls:** * **Hierarchy of Sensitivity:** Neurons > Cardiac Myocytes > Renal Tubular Cells > Hepatocytes > Skeletal Muscle > Fibroblasts/Epidermis [1]. * **Vulnerable Brain Zones:** The Hippocampus (CA1) is the first area to show signs of ischemic encephalopathy. * **Most Resistant:** Fibroblasts and skeletal muscle can survive for several hours of ischemia [1]. **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 Central Nervous System, pp. 1265-1266. [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. 246-247. [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. 150-151.

Question 1083: All of the following are true about C-reactive protein EXCEPT:

A. CRP is a positive acute-phase reactant.
B. It belongs to the beta globin family.
C. CRP is so named because it precipitates with the C-Carbohydrate antigen of pneumococcus.
D. It is specific to pneumococcal infections. (Correct Answer)

Explanation: C-reactive protein (CRP) is a classic **positive acute-phase reactant** synthesized by the liver in response to inflammatory cytokines, particularly **IL-6** [1]. **Why Option D is the correct answer (The Exception):** CRP is a **non-specific marker** of inflammation. While it was originally discovered in the sera of patients with pneumonia, its elevation is not limited to pneumococcal infections. It rises significantly in response to any acute tissue injury, bacterial infections, trauma, malignancy, or autoimmune flares. Therefore, stating it is "specific" to pneumococcal infections is medically incorrect. **Analysis of other options:** * **Option A:** CRP is a "positive" reactant because its plasma concentration increases (often up to 100-1000 fold) during acute inflammation [1]. * **Option B:** On serum protein electrophoresis, CRP migrates within the **gamma or beta-globulin fraction** (specifically belonging to the pentraxin family of proteins). * **Option C:** The name "C-reactive" is derived from its historical ability to bind and precipitate the **C-polysaccharide (C-substance)** found in the cell wall of *Streptococcus pneumoniae* [2]. **High-Yield NEET-PG Pearls:** * **Mechanism:** CRP acts as an **opsonin**; it binds to phosphocholine on microbes and activates the classical complement pathway (C1q) [2]. * **Clinical Use:** It is used to monitor disease activity in conditions like Rheumatoid Arthritis or Giant Cell Arteritis. * **hs-CRP (High-sensitivity CRP):** Used as a biomarker for **cardiovascular risk stratification**, reflecting low-grade chronic inflammation in atherosclerosis [2]. * **Half-life:** It has a short half-life (approx. 19 hours), making it a sensitive indicator of the "current" inflammatory status compared to ESR. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 111. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 501-502.

Question 1084: The AA amyloid chain is typically found in which of the following conditions?

A. Multiple myeloma
B. Rheumatoid arthritis (Correct Answer)
C. Gout
D. All of the above

Explanation: **Explanation:** **1. Why Rheumatoid Arthritis is Correct:** AA (Amyloid Associated) amyloidosis is a form of **Secondary (Reactive) Amyloidosis**. It occurs due to chronic inflammatory conditions or chronic infections [1]. In these states, cytokines (specifically IL-1 and IL-6) stimulate the liver to produce **Serum Amyloid A (SAA)** protein, an acute-phase reactant. Prolonged elevation of SAA leads to its limited proteolysis, forming AA amyloid fibrils [4]. **Rheumatoid Arthritis** is the most common cause of secondary amyloidosis in the developed world [2]. Other causes include Bronchiectasis, Osteomyelitis, and Inflammatory Bowel Disease [1]. **2. Why the Other Options are Incorrect:** * **Multiple Myeloma:** This is associated with **AL (Amyloid Light chain)** amyloidosis, also known as Primary Amyloidosis [3]. Here, malignant plasma cells produce excessive monoclonal immunoglobulin light chains (usually Lambda), which are then deposited as amyloid [3]. * **Gout:** While Gout is an inflammatory condition, it is characterized by the deposition of Monosodium Urate (MSU) crystals, not amyloid. It does not typically lead to systemic AA amyloidosis. * **All of the above:** Incorrect because the biochemical nature of amyloid (AA vs. AL) differs strictly based on the underlying pathology. **3. High-Yield Clinical Pearls for NEET-PG:** * **Staining:** All amyloid shows **Apple-green birefringence** under polarized light when stained with **Congo Red**. * **AA Protein:** Derived from SAA (liver-derived); associated with chronic inflammation [1]. * **AL Protein:** Derived from Ig Light Chains (plasma cell-derived); associated with Plasma Cell Dyscrasias [3]. * **ATTR Protein:** Found in Senile Systemic Amyloidosis and Familial Amyloid Polyneuropathies (Transthyretin) [1]. * **Aβ2-microglobulin:** Associated with long-term hemodialysis [1]. * **Diagnosis:** Abdominal fat pad biopsy or rectal biopsy are the preferred initial screening tests. **References:** [1] 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. 136-140. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 678-679. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 266-267. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 267-268.

Question 1085: A 20-year-old carpenter presents with an enlarged and tender lymph node in the axilla due to a wound infection on his left thumb. A lymph node biopsy shows follicular enlargement and hyperemia, with sinuses filled with neutrophils. What is the most likely diagnosis?

A. Suppurative lymphadenitis (Correct Answer)
B. Castleman disease
C. Interfollicular hyperplasia
D. Sinus histiocytosis

Explanation: **Explanation:** The clinical presentation and histopathology point towards **Suppurative (Acute) Lymphadenitis**. [1] **1. Why the correct answer is right:** The patient has an acute pyogenic infection (wound infection on the thumb) leading to regional lymphadenitis. [2] In **acute nonspecific lymphadenitis**, the nodes are physically enlarged, tender, and hyperemic. [1] Microscopically, the presence of **neutrophils** within the lymphoid sinuses and follicles is the hallmark of a suppurative process, often caused by organisms like *Staphylococcus aureus* or *Streptococcus pyogenes*. [1] If the infection progresses, it can lead to abscess formation (liquefactive necrosis). [1] **2. Why the incorrect options are wrong:** * **Castleman disease:** This is a rare lymphoproliferative disorder characterized by "lollipop" follicles (hyaline-vascular type) or plasma cell infiltration. It is not an acute inflammatory response to a peripheral wound. * **Interfollicular hyperplasia:** This involves expansion of the T-cell zones between follicles. It is typically seen in viral infections or post-vaccination, not in acute bacterial infections dominated by neutrophils. * **Sinus histiocytosis:** Also known as Rosai-Dorfman disease or a reactive pattern in cancer-draining nodes, it is characterized by the expansion of sinuses by **macrophages** (histiocytes), not neutrophils. **3. NEET-PG High-Yield Pearls:** * **Tender vs. Non-tender:** Inflammatory/Infectious nodes are usually **tender**; Malignant nodes (Lymphoma/Metastasis) are usually **painless** and firm. [1] * **Follicular Hyperplasia:** Associated with B-cell activation (e.g., Rheumatoid Arthritis, early HIV, Toxoplasmosis). * **Paracortical Hyperplasia:** Associated with T-cell activation (e.g., Viral infections like Infectious Mononucleosis). * **Starry-sky appearance:** Classically seen in Burkitt Lymphoma due to tingible body macrophages. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 592-593. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 85-86.

Question 1086: Which of the following is NOT a disease phenotype of Prion diseases?

A. Creutzfeldt-Jakob disease
B. Gerstmann-Straussler-Scheinker syndrome
C. Fatal familial insomnia
D. Leigh syndrome (Correct Answer)

Explanation: **Explanation:** Prion diseases (transmissible spongiform encephalopathies) are a group of neurodegenerative conditions caused by the accumulation of **PrPSc**, an abnormally folded isoform of the host-encoded prion protein (PrPc) [1], [4]. These diseases are characterized by neuronal loss, gliosis, and "spongiform" change in the brain [3]. **Why Leigh Syndrome is the correct answer:** Leigh syndrome (Subacute Necrotizing Encephalomyelopathy) is **not** a prion disease. It is a rare, progressive **mitochondrial disorder** typically presenting in infancy [2]. It is caused by mutations in mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) that affect the oxidative phosphorylation pathway (Complex I, II, IV, or V), leading to bilateral symmetrical necrotic lesions in the basal ganglia and brainstem [2]. **Analysis of Prion Disease Phenotypes (Incorrect Options):** * **Creutzfeldt-Jakob disease (CJD):** The most common human prion disease. It presents as rapidly progressive dementia with myoclonus and characteristic periodic sharp wave complexes on EEG [1]. * **Gerstmann-Sträussler-Scheinker (GSS) syndrome:** An autosomal dominant inherited prion disease caused by mutations in the *PRNP* gene [4]. It typically presents with chronic progressive ataxia and cognitive decline. * **Fatal Familial Insomnia (FFI):** An inherited prion disease characterized by severe sleep disturbances (insomnia), autonomic dysfunction, and selective atrophy of the thalamic nuclei [3]. **NEET-PG High-Yield Pearls:** * **PrPSc** is rich in **beta-pleated sheets**, making it resistant to proteases (unlike the alpha-helix rich PrPc) [4]. * Prions are highly resistant to standard sterilization; they require **autoclaving at 134°C** or immersion in **1N Sodium Hydroxide (NaOH)** [1]. * **Kuru** is a historical prion disease associated with ritualistic cannibalism [3]. * **Variant CJD (vCJD)** is linked to bovine spongiform encephalopathy ("Mad Cow Disease") and often shows "florid plaques" on histology [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 712-713. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1247-1248. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1284-1286. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, p. 1284.

Question 1087: An infant is brought in by his mother, who says that his skin tastes salty. The infant's pancreas is expected to undergo progressive fibrosis with atrophy of the exocrine glands and cystic dilation of the ducts. What is the basic underlying cellular abnormality?

A. Decreased synthesis of a surface receptor
B. Decreased intracellular cyclic AMP (cAMP)
C. Decreased function of a glycosylated chloride channel (Correct Answer)
D. Increased phosphorylation of a chloride channel

Explanation: **Explanation:** The clinical presentation of "salty-tasting skin" in an infant, combined with pancreatic fibrosis and cystic ductal dilation, is a classic description of **Cystic Fibrosis (CF)**. **1. Why the Correct Answer is Right:** Cystic Fibrosis is caused by a mutation in the **CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene** on chromosome 7 [2]. The CFTR protein is a **glycosylated, cAMP-gated chloride channel** located on the apical membrane of epithelial cells [3]. In the most common mutation (ΔF508), the protein misfolds in the endoplasmic reticulum, leading to its degradation before it reaches the cell surface [3]. This results in the **decreased function/absence** of the chloride channel [4]. In the pancreas, this leads to thick, inspissated secretions that obstruct ducts, causing atrophy and fibrosis. **2. Why Incorrect Options are Wrong:** * **Option A:** CF is a defect in a **channel/transporter**, not a surface receptor (unlike Familial Hypercholesterolemia, which involves the LDL receptor) [1]. * **Option B:** While CFTR is regulated by cAMP, the primary defect is in the channel protein itself, not a deficiency in the intracellular secondary messenger (cAMP). * **Option C (Correct):** Reflects the lack of functional CFTR protein at the plasma membrane. * **Option D:** CFTR is activated by phosphorylation via Protein Kinase A. Increased phosphorylation would theoretically increase channel activity, which is the opposite of the pathology seen in CF. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most Common Mutation:** ΔF508 (Class II mutation: protein trafficking defect) [3]. * **Diagnosis:** Sweat Chloride Test (Gold Standard) – Chloride levels >60 mEq/L [5]. * **Pancreas:** Leads to malabsorption and Steatorrhea; eventually causes CF-related diabetes. * **Lungs:** Recurrent infections; *Pseudomonas aeruginosa* is the most common pathogen in older children [4]. * **Reproductive System:** Bilateral Absence of Vas Deferens (CBAVD) leading to infertility in males [5]. **References:** [1] 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. 93-94. [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. 120-122. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, p. 476. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Lumen Of Sweat Duct, pp. 475-476. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 478-479.

Question 1088: Subluxated lens, thin elongated extremities, hyperextensible extremities, and aortic aneurysm are the characteristic clinical features of which of the following conditions?

A. Marfan's syndrome (Correct Answer)
B. Ehlers-Danlos syndrome
C. Homocystinuria
D. Klinefelter's syndrome

Explanation: **Explanation:** The clinical presentation described is classic for **Marfan’s syndrome**, an autosomal dominant disorder of connective tissue. [1] **1. Why Marfan’s Syndrome is Correct:** The underlying defect is a mutation in the **FBN1 gene** on chromosome 15, which encodes **Fibrillin-1**. Fibrillin-1 is a major component of microfibrils that act as a scaffold for elastin. Deficiency leads to: * **Skeletal:** Arachnodactyly (thin, long fingers) and dolichostenomelia (long extremities). [1] * **Ocular:** **Ectopia lentis** (subluxation of the lens), typically **upward and outward**. * **Cardiovascular:** Cystic medial necrosis of the aorta, leading to **Aortic Aneurysm** and dissection (the most common cause of death). **2. Why Other Options are Incorrect:** * **Ehlers-Danlos Syndrome (EDS):** While EDS features hyperextensible skin and hypermobile joints, it is primarily a defect in **collagen synthesis**. [2] It does not typically present with the "marfanoid" tall stature or lens subluxation. * **Homocystinuria:** This mimics Marfan’s (tall stature, lens subluxation), but the lens displacement is typically **downward and inward**. Crucially, it is associated with **intellectual disability** and a high risk of **thromboembolism**, which are absent in Marfan’s. * **Klinefelter’s Syndrome (47, XXY):** Patients are tall with long legs, but they present with testicular atrophy, gynecomastia, and infertility, not connective tissue fragility or lens subluxation. **High-Yield Clinical Pearls for NEET-PG:** * **Steinberg Sign:** Thumb projects beyond the ulnar border of the clenched fist (seen in Marfan’s). * **Walker-Murdoch Sign:** Thumb and fifth finger overlap when encircling the opposite wrist. * **TGF-β:** Fibrillin-1 normally sequesters TGF-β; its deficiency leads to excess TGF-β signaling, contributing to aortic weakening. [1] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 153-154. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 154-155.

Question 1089: Which CD marker is associated with cytotoxic T-lymphocytes?

A. CD 4
B. CD 8 (Correct Answer)
C. CD 21
D. CD 45

Explanation: ### Explanation **Correct Option: B (CD 8)** Cytotoxic T-lymphocytes (CTLs) are a subtype of T-cells responsible for the direct destruction of virally infected cells and tumor cells [1]. They are characterized by the expression of the **CD8** surface marker. These cells recognize antigens presented by **MHC Class I** molecules (Rule of 8: 8 × 1 = 8) [2]. Upon activation, they release perforins and granzymes to induce apoptosis in target cells. **Analysis of Incorrect Options:** * **CD 4 (Option A):** This marker is associated with **Helper T-lymphocytes (Th cells)** [3]. They recognize antigens presented by **MHC Class II** molecules (Rule of 8: 4 × 2 = 8) and coordinate the immune response by secreting cytokines. * **CD 21 (Option B):** This is a marker for **B-lymphocytes**. It also serves as the receptor for the **Epstein-Barr Virus (EBV)**, facilitating its entry into B-cells (leading to Infectious Mononucleosis). * **CD 45 (Option D):** Known as the **Leukocyte Common Antigen (LCA)**, it is expressed on all hematopoietic cells (except mature erythrocytes and platelets). It is used in immunohistochemistry to differentiate lymphomas from carcinomas. **High-Yield Clinical Pearls for NEET-PG:** * **CD3:** The pan-T-cell marker (present on both CD4+ and CD8+ cells) [3]. * **CD19, CD20, CD21:** Classic B-cell markers. * **CD16/CD56:** Markers for Natural Killer (NK) cells. * **CD15/CD30:** Positive in Reed-Sternberg cells (Hodgkin Lymphoma), except in the lymphocyte-predominant subtype. * **CD34:** Marker for hematopoietic stem cells. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 240. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 318-319. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 198-199.

Question 1090: Which of the following growth alterations is an example of hyperplasia rather than metaplasia?

A. Increased goblet cells in the mainstem bronchus of a smoker (Correct Answer)
B. Squamous epithelium in the bladder of a patient with Schistosoma haematobium
C. Distal esophagus with glandular epithelium intermixed with squamous epithelium
D. Goblet and Paneth cells in the glands of the gastric mucosa

Explanation: ### Explanation The core concept tested here is the distinction between **Hyperplasia** (increase in the number of cells of the same type) [2] and **Metaplasia** (replacement of one adult cell type by another adult cell type of the same germ layer). **1. Why Option A is Correct:** In the mainstem bronchus of a smoker, the chronic irritation of tobacco smoke causes the pre-existing **goblet cells** (which are normally present in the respiratory epithelium) to increase in number to produce more mucus for protection [1]. Since the cell type remains the same but increases in quantity, this is **Goblet Cell Hyperplasia** [1]. **2. Why the Other Options are Incorrect:** * **Option B (Bladder):** Chronic irritation by *Schistosoma haematobium* eggs causes the normal transitional epithelium (urothelium) to change into **Squamous epithelium**. This is Squamous Metaplasia, a precursor to Squamous Cell Carcinoma of the bladder. * **Option C (Distal Esophagus):** This describes **Barrett’s Esophagus**, where the stratified squamous epithelium of the esophagus is replaced by columnar (glandular) epithelium due to chronic acid reflux. This is a classic example of Intestinal Metaplasia. * **Option D (Gastric Mucosa):** The presence of Goblet and Paneth cells in the stomach (where they are normally absent) indicates **Intestinal Metaplasia**, often seen in chronic *H. pylori* gastritis. **3. NEET-PG High-Yield Pearls:** * **Metaplasia** is a reversible change but, if the stimulus persists, it can progress to dysplasia and neoplasia. * **Exception to the rule:** While most metaplasia involves a change to a "tougher" cell type, Barrett’s esophagus is a change from squamous to columnar (more acid-resistant). * **Vitamin A deficiency** can lead to squamous metaplasia in the respiratory tract and ducts of glands (e.g., xerophthalmia). * **Connective tissue metaplasia:** Formation of bone in soft tissue (e.g., Myositis Ossificans) is also a form of metaplasia. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 723. [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. 85-88.

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