Q- A 70-year-old man dies 2 weeks after an ischemic stroke. At autopsy, the infarcted brain tissue is soft and partly cystic. Which type of necrosis is this?
A- Coagulative necrosis
B- Liquefactive necrosis
C- Caseous necrosis
D- Fat necrosis
B- Liquefactive necrosis. Ischemic injury in the brain causes liquefactive necrosis because neural tissue is rich in lipids and enzymes, and microglia digest the dead tissue. Ischemia in most other solid organs (heart, kidney) causes coagulative necrosis. Caseous necrosis is typical of tuberculosis, and fat necrosis of acute pancreatitis.
Q- A patient with multiple myeloma develops nephrotic syndrome. A renal biopsy shows deposits that stain with Congo red and show apple-green birefringence under polarized light. What are the deposits made of?
A- Immunoglobulin light chains (AL)
B- Serum amyloid A (AA)
C- Transthyretin (ATTR)
D- Beta-2 microglobulin
A- Immunoglobulin light chains (AL amyloid). AL amyloidosis is associated with plasma cell disorders such as multiple myeloma. AA amyloid occurs with chronic inflammation (rheumatoid arthritis, tuberculosis), ATTR causes cardiac amyloidosis in older adults and familial neuropathy, and beta-2 microglobulin amyloid occurs in long-term dialysis patients.
Q- A 60-year-old man with cirrhosis from chronic hepatitis C has weight loss and a new liver mass. Which serum tumor marker is most likely elevated?
A- Alpha-fetoprotein (AFP)
B- CA 19-9
C- CA-125
D- Carcinoembryonic antigen (CEA)
A- Alpha-fetoprotein. AFP is elevated in hepatocellular carcinoma (and in yolk sac tumors). CA 19-9 is used for pancreatic cancer, CA-125 for ovarian cancer, and CEA for colorectal cancer. Tumor markers help with monitoring but are not used alone for diagnosis.
Q- During an infection, IL-1, IL-6, and TNF-alpha act on the hypothalamus to raise the body temperature set point. Which mediator directly causes this effect in the hypothalamus?
A- Prostaglandin E2
B- Histamine
C- Leukotriene B4
D- Bradykinin
A- Prostaglandin E2. Pyrogenic cytokines induce COX in the hypothalamus, increasing PGE2, which raises the temperature set point. NSAIDs and acetaminophen reduce fever by blocking prostaglandin synthesis. Histamine causes vasodilation and increased permeability, leukotriene B4 attracts neutrophils, and bradykinin causes pain.
Q- A 55-year-old man with long-standing reflux has an endoscopic biopsy showing that the distal esophageal squamous epithelium has been replaced by columnar epithelium with goblet cells. Which cancer is he at increased risk for?
A- Esophageal adenocarcinoma
B- Esophageal squamous cell carcinoma
C- Gastric MALT lymphoma
D- Esophageal leiomyoma
A- Esophageal adenocarcinoma. This is Barrett esophagus, an intestinal metaplasia caused by chronic acid reflux. It can progress to dysplasia and adenocarcinoma of the distal esophagus. Squamous cell carcinoma usually affects the upper and middle esophagus and is linked to smoking and alcohol.
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