A 47-year-old man with metastatic ileal neuroendocrine tumor develops edema and hepatomegaly. Echocardiography shows tricuspid regurgitation and pulmonary stenosis. Autopsy would be expected to show:

• A Commissural fusion of both mitral and aortic valves
• B Large friable vegetations containing bacteria on the mitral valve
• C Fibrous plaques on right-sided valvular endocardium with intact underlying architecture ✓
• D Mucinous expansion of all four valve spongiosa layers

Explanation

Serotonin released by liver metastases escapes first-pass metabolism and drives plaque-like endocardial and valvular fibrosis confined to the right side of the heart, since the pulmonary bed degrades the mediator before it reaches left valves. The fibrous deposits thicken cusps and chordae while leaving valve structure otherwise intact. Myxomatous change of all four valves describes mitral valve prolapse, not carcinoid disease.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.