This 48-year-old man underwent tricuspid valve replacement for severe mixed regurgitation and stenosis. His pulmonary valve showed mild abnormalities on echo, while his mitral and aortic valves were unaffected.
Gross findings: Carcinoid heart disease presents as white-tan “stuck-on” plaques on valves and endocardial surfaces. Classically, it will lack disruption of the underlying valve itself, distinguishing it from destructive lesions like endocarditis, and acquired structural changes like myxomatous disease and postinflammatory (rheumatic) disease. The plaques hinder a valve’s ability to move and thus results in functional disruption (regurg, stenosis, or mixed disease). Note also that there is no tumor in carcinoid heart disease. It also preferentially affects the right heart.
What gross features and clues in the history helped with the differential?
More about this amazing disease:
The interaction of serotonin and other vasoactive compounds elaborated by a carcinoid tumor with the endocardium can result in this pathology.
Serotonin is metabolized to 5-hydroxyindoleacetic acid (5-HIAA) by monoamine oxidase and aldehyde dehydrogenase. This occurs in the liver, lungs, and (to an extent) brain. If serotonin bypasses hepatic metabolism and drains directly into the inferior vena cava (either from hepatic mets or a gonadal primary), it exposes the right heart to the serotonin-rich blood. The current theory hypothesizes that the presence of monoamine oxidase in the lungs leads to serotonin metabolism before the blood reaches the left heart, thereby sparing the mitral and aortic valves and leading to an exquisitely right-sided presentation (hence the tricuspid valve pathology in this case). Rarely, lymph node metastases may also contribute to carcinoid heart disease via thoracic duct drainage.
Serotonin receptors on the cardiac valves are activated by the serotonin-rich environment, leading to the classic histologic picture of fibroproliferative spindle cells with tapered ends in a loose, myxoid background. These lesions have a "stuck on" appearance on microscopy, affecting the upstream surface of the valve without damage to the underlying valvular architecture (as pictured in the VVG attachment).
The most common valvulopathies associated with carcinoid heart disease are tricuspid valve regurgitation and mixed pulmonary valve insufficiency and stenosis. This occurs due to valvular retraction, fibrotic thickening, and commissural fusion. As seen in the gross image, the chordae tendineae are foreshortened, thickened, and fused in this disease.
The presence of carcinoid heart disease is associated with a worse three-year survival in patients with carcinoid syndrome, emphasizing the importance of recognizing this disease on surgical pathology. For more information see this review by Hassan et al.
- Melanie Bois
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