USMLE Step 1 Question 352

Question:

A 65-year-old man with a history of mitral valve prolapse presents with fever and weight loss after a recent dental procedure. At one week in the hospital, he has acute left flank pain. A CT shows a wedge-shaped area of hypoperfusion in the left kidney. If a biopsy of this area were done, what would it show?

Correct Answer: C.  Coagulative necrosis

The man presumably has bacterial endocarditis (likely Strep viridans) that occurred when oral flora entered his bloodstream during a dental procedure and infected his abnormal heart valve. A complication of endocarditis is systemic septic emboli, often to the spleen or kidney. Tissue death due to hypoperfusion is called coagulative necrosis.

An exception is hypoperfusion to brain tissue, in which for unknown reasons, dead tissue is dissolved, a process called liquefactive necrosis (choice E).

Caseous necrosis (choice B) is most often associated with tuberculous granulomas, appearing “cheese-like” on microscopy.

Atrophy (choice A) is shrinkage of normal tissue, as occurs with unused muscle tissue.

Dysplasia (choice D) refers to abnormal changes in cell architecture that occurs in pre-malignant or malignant tumors. Generally, dysplasia indicates proliferation of immature cells with a corresponding decrease in the number of mature cells.