General Pathology Practice Questions

Q: Which is the most likely inheritance pattern of the disease shown in the family pedigree?

X-Linked dominant type. ***X-Linked dominant type*** - **Affected fathers** pass the condition to **all daughters** but **no sons**, as fathers pass their X chromosome only to daughters. - **Affected females** appear in **every generation** with **vertical transmission**, distinguishing it from X-linked recessive patterns. *Autosomal recessive type* - Would show **horizontal transmission** with affected siblings but unaffected parents in typical cases. - Both **males and females** would be equally affected, and **consanguinity** would often be present in family history. *Autosomal dominant type* - Would show **equal transmission** to both male and female offspring from affected parents. - **Affected fathers** would pass the condition to approximately **50% of both sons and daughters**, not exclusively to daughters. *X-linked recessive type* - Would primarily affect **males** with **carrier females** who are typically unaffected. - Shows **knight's move pattern** with affected males related through unaffected carrier females, and **no male-to-male transmission**.

Q: Telomerase activity is expressed in which of the following cell types?

Germ cells. **Explanation:** **1. Why Germ Cells are Correct:** Telomerase is a specialized ribonucleoprotein enzyme (a reverse transcriptase) that adds TTAGGG repeats to the ends of chromosomes (telomeres). In most somatic cells, telomerase is absent; therefore, telomeres shorten with every cell division, eventually leading to replicative senescence (the Hayflick limit). However, **germ cells** (and stem cells) must maintain their telomere length to ensure that genetic information is passed intact to the next generation [1]. High telomerase activity in germ cells allows them to divide indefinitely without losing chromosomal integrity [1]. **2. Why Other Options are Incorrect:** * **Myocytes (A) and Osteocytes (C):** These are terminally differentiated, permanent, or stable cells. They lack telomerase activity. As they age or undergo limited repair, their telomeres shorten, contributing to cellular aging. * **Keratinocytes (B):** While basal epithelial cells (stem cells) have some telomerase activity, mature keratinocytes are differentiated somatic cells that eventually lose this activity as they move toward the stratum corneum and undergo programmed cell death. **3. High-Yield Clinical Pearls for NEET-PG:** * **Cancer Connection:** Approximately **85-90% of human cancer cells** upregulate telomerase [1]. This is a hallmark of "immortality" in malignancy, allowing tumor cells to bypass senescence [1]. * **Stem Cells:** Telomerase is present at low levels in somatic stem cells (e.g., hematopoietic stem cells) but is highest in germ cells [1]. * **Shelterin Complex:** This is a group of proteins that binds to telomeres to protect chromosome ends from being mistaken for double-stranded DNA breaks. * **Progeria (Hutchinson-Gilford Syndrome):** A condition of premature aging often linked to accelerated telomere attrition. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 311-312.

Q: A 3-year-old boy presents to the emergency room with acute distress, vague chest pain, and difficulty swallowing. He refuses to drink water. Physical examination reveals drooling and salivation. Vital signs are normal. The mother reports the child ingested a liquid drain cleaner. If this chemical was a strong acid, what histopathologic finding would be expected in the esophagus?

Coagulative necrosis. **Explanation:** The ingestion of corrosive substances leads to severe tissue damage through different mechanisms depending on the pH of the agent. **1. Why Coagulative Necrosis is Correct:** Strong acids (e.g., sulfuric acid, hydrochloric acid) cause **coagulative necrosis**. When acid contacts the esophageal or gastric mucosa, it causes rapid dehydration of cells and denaturation of proteins. This process creates a firm, thick, and leathery **eschar (scab)**. This eschar acts as a physical barrier, limiting the further deep penetration of the acid into the muscular layers of the organ. This is why acid ingestions often result in more superficial damage to the esophagus compared to alkalis, though they frequently cause severe damage to the stomach (pyloric stenosis). **2. Why Other Options are Incorrect:** * **Apoptosis:** This is programmed cell death and is not the mechanism of acute chemical trauma. * **Fat Necrosis:** This is typically seen in acute pancreatitis or breast tissue trauma, involving the action of lipases on fatty tissue. * **Hyaline Sclerosis:** This refers to chronic scarring and thickening of vessel walls or tissues, not an acute necrotic process following chemical ingestion. **3. High-Yield Clinical Pearls for NEET-PG:** * **Alkalis (e.g., Drain cleaners, Lye):** Cause **Liquefactive Necrosis**. They saponify fats and dissolve proteins, allowing the chemical to penetrate deeply into the tissues, often leading to esophageal perforation. * **Site of Injury:** Alkalis primarily affect the **esophagus**, while acids primarily affect the **stomach** (due to gastric spasms and the protective eschar in the esophagus). * **Antidote Rule:** Never attempt to neutralize the substance with a weak acid/base, as the resulting exothermic reaction can cause thermal burns. Gastric lavage and emesis are generally contraindicated in corrosive poisoning.

Q: All of the following are TRUE regarding myoglobinuria, EXCEPT:

The serum is deep red in color.. **Explanation:** The key to answering this question lies in understanding the physiological handling of myoglobin versus hemoglobin. **1. Why Option D is the correct (False) statement:** Myoglobin is a small monomeric protein (17,000 Daltons) with a very low renal threshold. Once released from damaged muscle, it is rapidly cleared from the circulation by the kidneys. Consequently, even in severe rhabdomyolysis, the **serum remains clear (normal color)** because myoglobin does not accumulate in the plasma. In contrast, **hemoglobinuria** is associated with pink or red serum (hemoglobinemia) because hemoglobin binds to haptoglobin, creating a large complex that lingers in the circulation [1]. **2. Analysis of Incorrect Options (True Statements):** * **Option A:** Myoglobin is the primary oxygen-binding pigment found in all striated muscles, including both skeletal and cardiac muscle fibers. * **Option B:** For myoglobin to be visible to the naked eye (causing red-brown or "cola-colored" urine), approximately **200 grams** of muscle destruction is required. * **Option C:** The Benzidine test (and the orthotoluidine dipstick) detects the peroxidase activity of the heme group. Since myoglobin contains heme, it will yield a **positive** result, similar to hemoglobin. **Clinical Pearls for NEET-PG:** * **Differential Diagnosis:** To distinguish myoglobinuria from hemoglobinuria, observe the serum. **Clear serum + Red urine = Myoglobinuria**; **Red serum + Red urine = Hemoglobinuria.** * **Renal Impact:** Myoglobin is nephrotoxic; in acidic urine, it precipitates with Tamm-Horsfall protein to form "pigment casts," leading to Acute Tubular Necrosis (ATN) [1]. * **Biochemical Marker:** Serum Creatine Kinase (CK) levels are significantly elevated in cases of myoglobinuria. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 639-640.

Q: Which sign is most pathognomonic of irreversible cell injury?

Amorphous densities in mitochondria. ### Explanation The hallmark of **irreversible cell injury** is the inability to reverse mitochondrial dysfunction and profound disturbances in membrane function. **1. Why "Amorphous densities in mitochondria" is correct:** The appearance of large, flocculent, **amorphous densities** (composed of proteins, lipids, and calcium) within the mitochondrial matrix is the most specific morphological sign of irreversible injury. It signifies severe mitochondrial damage, leading to a permanent failure of oxidative phosphorylation and ATP production. Once these densities appear, the cell can no longer recover even if oxygenation is restored. **2. Why the other options are incorrect:** * **B. Swelling of the cell membrane:** This is a feature of **reversible injury** (cellular swelling or hydropic change). It occurs due to the failure of ATP-dependent Na⁺-K⁺ pumps, leading to an influx of water. * **C. Ribosomes detached from ER:** This occurs during **reversible injury**. When the cell swells, the endoplasmic reticulum (ER) dilates, causing ribosomes to detach, which leads to a transient decrease in protein synthesis. * **D. Clumping of the nucleus:** Chromatin clumping is an **early, reversible change** caused by a decrease in intracellular pH (lactic acidosis) due to anaerobic glycolysis. **NEET-PG High-Yield Pearls:** * **Point of No Return:** Defined by two phenomena: inability to reverse mitochondrial dysfunction and profound membrane damage (plasma and lysosomal). * **Nuclear Changes in Irreversibility:** Pyknosis (shrinkage), Karyorrhexis (fragmentation), and Karyolysis (dissolution). * **Earliest Light Microscopic Change:** Cellular swelling (Reversible). * **Earliest Ultrastructural Change:** Mitochondrial swelling (Reversible). Note: *Swelling* is reversible; *Amorphous densities* are irreversible.

Q: Which of the following is the most common fixative used in electron microscopy?

Glutaraldehyde. Because no provided references [1-5] match the topic of electron microscopy fixatives, this explanation remains uncited. **Explanation:** **1. Why Glutaraldehyde is the Correct Answer:** In electron microscopy (EM), the goal is to preserve the cell's ultrastructure at a macromolecular level. **Glutaraldehyde** is a dialdehyde that forms extensive cross-links between proteins much more rapidly and effectively than formaldehyde. This creates a stable "lattice" that preserves fine details of organelles (like mitochondria and ribosomes) and prevents artifacts during the high-vacuum conditions of EM. It is typically followed by secondary fixation with **Osmium Tetroxide** to preserve lipids and provide contrast. **2. Why the Other Options are Incorrect:** * **Formalin (10% Buffered):** This is the standard fixative for **Light Microscopy**. While it penetrates tissues quickly, its cross-linking is reversible and insufficient to preserve the ultra-fine details required for EM. * **Picric Acid:** This is a component of **Bouin’s fluid**. It is excellent for preserving glycogen and soft tissues (like endocrine organs) for light microscopy but causes significant shrinkage, making it unsuitable for EM. * **Absolute Alcohol:** This is a **precipitating fixative**. It acts by denaturing proteins and removing water, which causes severe distortion of the cellular morphology and "ghost-like" appearances of organelles. **3. High-Yield Clinical Pearls for NEET-PG:** * **Best Fixative for EM:** Glutaraldehyde (Primary) + Osmium Tetroxide (Secondary). * **Best Fixative for Routine Histopathology:** 10% Neutral Buffered Formalin. * **Fixative for Testicular Biopsy:** Bouin’s Fluid (contains Picric acid). * **Fixative for Cytology (Pap Smear):** 95% Ethyl Alcohol. * **Karnovsky’s Fixative:** A mixture of glutaraldehyde and paraformaldehyde often used in advanced structural research.

Q: Which stain is NOT used for lipids?

Congo red. **Explanation:** The correct answer is **Congo red** because it is the gold-standard stain for **Amyloid**, not lipids. 1. **Why Congo red is the correct answer:** Congo red is a specific stain used to identify amyloid fibrils. Under ordinary light, it stains amyloid pink-red [1]. However, its diagnostic hallmark is seen under **polarized microscopy**, where amyloid exhibits a characteristic **apple-green birefringence** [1, 2]. It has no affinity for lipid molecules. 2. **Why the other options are incorrect:** * **Oil Red O:** This is a lysochrome (fat-soluble) dye used specifically to demonstrate neutral triglycerides and lipids in frozen sections. It imparts a bright red color to fat droplets. * **Sudan III & Sudan Black B:** These are the most common stains for lipids. Sudan III stains lipids orange-red, while Sudan Black B is the most sensitive of the Sudan dyes, staining neutral fats black. Sudan Black is also used in hematopathology to differentiate AML (positive) from ALL (negative). **NEET-PG High-Yield Pearls:** * **Processing Requirement:** To stain lipids, tissues must be processed as **frozen sections**. Conventional paraffin embedding involves alcohols and xylol, which dissolve lipids, leaving behind empty vacuoles (clear spaces). * **Other Lipid Stains:** Osmium tetroxide (stains fat black and is used for electron microscopy). * **Amyloid Stains:** Apart from Congo red, other stains include Thioflavin T/S (fluorescent) and Crystal violet (metachromatic). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 268-269. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 580-581.

Question 1

Which is the most likely inheritance pattern of the disease shown in the family pedigree?

Accepted Answer

X-Linked dominant type

Answer

Autosomal recessive type

Answer

Autosomal dominant type

Answer

X-linked recessive type

Question 2

Telomerase activity is expressed in which of the following cell types?

Accepted Answer

Germ cells

Answer

Myocytes

Answer

Keratinocytes

Answer

Osteocytes

Question 3

A 3-year-old boy presents to the emergency room with acute distress, vague chest pain, and difficulty swallowing. He refuses to drink water. Physical examination reveals drooling and salivation. Vital signs are normal. The mother reports the child ingested a liquid drain cleaner. If this chemical was a strong acid, what histopathologic finding would be expected in the esophagus?

Accepted Answer

Coagulative necrosis

Answer

Apoptosis

Answer

Fat necrosis

Answer

Hyaline sclerosis

Question 4

Decrease in cell size refers to which of the following cellular adaptations?

Accepted Answer

Atrophy

Answer

Metaplasia

Answer

Hyperplasia

Answer

Hypertrophy

Question 5

All of the following are TRUE regarding myoglobinuria, EXCEPT:

Accepted Answer

The serum is deep red in color.

Answer

Myoglobin is present in striated skeletal and cardiac fibers.

Answer

200 g of muscle must be destroyed to color the urine visibly.

Answer

Benzidine test performed on urine is positive.

Question 6

Which sign is most pathognomonic of irreversible cell injury?

Accepted Answer

Amorphous densities in mitochondria

Answer

Swelling of the cell membrane

Answer

Ribosomes detached from endoplasmic reticulum

Answer

Clumping of the nucleus

Question 7

Which of the following is the most common fixative used in electron microscopy?

Accepted Answer

Glutaraldehyde

Answer

Formalin

Answer

Picric acid

Answer

Absolute alcohol

Question 8

Which stain is NOT used for lipids?

Accepted Answer

Congo red

Answer

Oil red

Answer

Sudan III

Answer

Sudan black

Question 9

Aneuploidy is due to:

Accepted Answer

Non-disjunction at meiosis

Answer

Mosaicism

Answer

Deletion

Answer

Translocation

Question 10

A CT scan of a 43-year-old woman with a parathyroid adenoma and hyperparathyroidism reveals extensive calcium deposits in the lungs and kidney parenchyma. These radiologic findings are best explained by which of the following mechanisms of disease?

Accepted Answer

Metastatic calcification

Answer

Arteriosclerosis

Answer

Dystrophic calcification

Answer

Granulomatous inflammation

General Pathology — MCQs

General Pathology — MCQs

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