USMLE Pathology

Question 1

A 55-year-old smoker presents with a central lung mass, hypercalcemia, and finger clubbing. Histology shows keratin pearls and intercellular bridges. What is the diagnosis?

Accepted Answer

Squamous cell carcinoma

Answer

Squamous cell carcinoma arises centrally, produces PTHrP causing hypercalcemia, and shows keratin pearls with intercellular bridges on histology.

Question 2

Which type of necrosis is characteristic of tuberculosis granulomas?

Accepted Answer

Caseous necrosis

Answer

Caseous necrosis is characteristic of granulomatous inflammation in TB, producing a cheese-like gross appearance due to incomplete digestion of cellular debris.

Question 3

A patient with SLE has a positive ANA and anti-dsDNA antibodies. Which type of hypersensitivity reaction mediates the kidney damage in lupus nephritis?

Accepted Answer

Type III (immune complex-mediated)

Answer

Lupus nephritis is caused by deposition of immune complexes (dsDNA-anti-dsDNA) in the glomerular basement membrane, activating complement and causing type III hypersensitivity injury.

Question 4

Which tumor marker is elevated in hepatocellular carcinoma?

Accepted Answer

Alpha-fetoprotein (AFP)

Answer

AFP is the primary tumor marker for hepatocellular carcinoma (HCC) and is also elevated in yolk sac tumors and in normal fetal liver.

Question 5

A 30-year-old woman has a breast mass that moves freely, is rubbery, and has well-defined borders. No lymph node involvement. What is the most likely diagnosis?

Accepted Answer

Fibroadenoma

Answer

Fibroadenoma is the most common benign breast tumor in young women, presenting as a well-circumscribed, rubbery, freely movable mass with no lymph node involvement.

USMLE Practice Test

USMLE Practice Test

USMLE Pathology