General Pathology Practice Questions

Q: A 28-year-old male presents with low-grade fever, night sweats, weight loss, and productive cough for 8 weeks. Chest X-ray shows a right upper lobe opacity with cavitation. Sputum AFB smear is positive. The lung biopsy histology is shown in Image 3. The type of necrosis seen at the centre of the lesion in this image is also characteristically found in which of the following conditions?

A. Tuberculosis and histoplasmosis. ***Tuberculosis and histoplasmosis*** - The clinical presentation and positive AFB smear indicate **Mycobacterium tuberculosis**, which causes **caseous necrosis**, characterized by a friable, white, "cheese-like" appearance. - **Histoplasmosis**, a fungal infection, is also a classic cause of **granulomatous inflammation** with central **caseous necrosis**, making it morphologically similar to tuberculosis. *Liquefactive necrosis in cerebral abscess* - **Liquefactive necrosis** is characterized by the total digestion of dead cells, resulting in a liquid viscous mass, common in **central nervous system** infarcts and bacterial abscesses. - Unlike caseous necrosis, it does not maintain a dry, granular appearance but rather forms a **liquid pus** or cystic space. *Coagulative necrosis in myocardial infarction* - **Coagulative necrosis** preserves the basic **structural outline** of the dead tissue for several days, typical of hypoxic cell death in all organs except the brain. - It lacks the amorphous, granular, and acellular "cheese-like" debris that defines the **caseating granulomas** seen in the provided scenario. *Fat necrosis in acute pancreatitis* - **Fat necrosis** refers to focal areas of fat destruction typically resulting from the release of activated **pancreatic lipases** into the peritoneum. - It is characterized by **saponification**, where fatty acids combine with calcium to produce macroscopic **chalky white deposits**, distinct from the granulomatous pattern of TB.

Q: A 4-year-old boy is brought to the emergency department after being found locked in a car on a summer day. His temperature is 105°F (40.6°C), he is lethargic, has decreased skin turgor, and laboratory studies show sodium 155 mEq/L, creatinine 1.8 mg/dL, and AST 250 U/L. Analyze the pathophysiological mechanism most responsible for his organ dysfunction.

Direct thermal injury to cellular proteins and membranes. ***Direct thermal injury to cellular proteins and membranes*** - Core temperatures exceeding **40°C (104°F)** lead to **protein denaturation** and cellular membrane collapse, which is the primary driver of multiorgan dysfunction in **heat stroke**. - This direct cytotoxicity explains the elevated **AST** (hepatic injury), **creatinine** (renal injury), and central nervous system symptoms like **lethargy**. *Bacterial endotoxin release* - While heat can damage the **intestinal mucosal barrier** allowing bacterial products to enter circulation, it is a secondary complication rather than the initiating mechanism. - Endotoxemia contributes to the **sepsis-like syndrome** seen in late-stage heat stroke but follows the initial thermal injury. *Widespread microvascular thrombosis* - This occurs during **Disseminated Intravascular Coagulation (DIC)**, which can be triggered by thermal injury to the **endothelium**. - Although a severe complication of heat stroke, it is a downstream effect of the inflammatory and thermal damage to vessel walls. *Acute tubular necrosis from dehydration alone* - The patient has **hypernatremia** and signs of dehydration, but the rapid elevation of **AST** and severe **hyperthermia** indicate a more systemic insult than volume depletion. - **Acute tubular necrosis (ATN)** in this context is caused by a combination of ischemia, **direct thermal damage**, and potentially **rhabdomyolysis**, not just dehydration. *Cytokine-mediated inflammatory response* - Heat stroke triggers a **systemic inflammatory response syndrome (SIRS)**, but this is a physiological reaction to the cellular damage already occurring. - High levels of **interleukins** and **TNF-alpha** worsen the condition, but the **direct thermal effect** is the root cause of the cellular death.

Question 1

A 45-year-old male presents with nephrotic syndrome, frothy urine, and bilateral pedal edema. Serum albumin is 2.1 g/dL. Urinalysis shows 4+ proteinuria. Renal biopsy is performed. The electron microscopy image is shown (Image 1), demonstrating subepithelial electron-dense deposits along the glomerular basement membrane. Which of the following best explains the pathogenesis of the glomerular injury seen in this condition?

Accepted Answer

A. In situ immune complex formation involving anti-PLA2R antibodies targeting podocyte antigens with complement-mediated injury

Answer

B. Circulating immune complex deposition in the mesangium activating the alternative complement pathway

Answer

C. Anti-GBM antibody binding to type IV collagen alpha-3 chain causing linear IgG deposits along the basement membrane

Answer

D. T-cell mediated cytokine release causing podocyte foot process effacement without immune complex deposition

Question 2

A 28-year-old male presents with low-grade fever, night sweats, weight loss, and productive cough for 8 weeks. Chest X-ray shows a right upper lobe opacity with cavitation. Sputum AFB smear is positive. The lung biopsy histology is shown in Image 3. The type of necrosis seen at the centre of the lesion in this image is also characteristically found in which of the following conditions?

Accepted Answer

A. Tuberculosis and histoplasmosis

Answer

B. Liquefactive necrosis in cerebral abscess

Answer

C. Coagulative necrosis in myocardial infarction

Answer

D. Fat necrosis in acute pancreatitis

Question 3

A 4-year-old boy is brought to the emergency department after being found locked in a car on a summer day. His temperature is 105°F (40.6°C), he is lethargic, has decreased skin turgor, and laboratory studies show sodium 155 mEq/L, creatinine 1.8 mg/dL, and AST 250 U/L. Analyze the pathophysiological mechanism most responsible for his organ dysfunction.

Accepted Answer

Direct thermal injury to cellular proteins and membranes

Answer

Bacterial endotoxin release

Answer

Widespread microvascular thrombosis

Answer

Acute tubular necrosis from dehydration alone

Answer

Cytokine-mediated inflammatory response

Question 4

Irreversible cell injury is primarily due to which of the following?

Accepted Answer

Irreversible damage to essential cellular components, such as membranes and proteins

Answer

Significant decrease in intracellular ATP levels

Answer

Formation of myelin figures

Answer

Cellular swelling due to osmotic changes

Question 5

Secondary amyloidosis complicates which of the following conditions?

Accepted Answer

Chronic osteomyelitis

Answer

Pneumonia

Answer

Chronic glomerulonephritis

Answer

Irritable bowel syndrome

General Pathology — MCQs

General Pathology — MCQs

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