Home   Chapter Home   Jobs   Conferences   Fellowships   Books


Small bowel (small intestine)

Other malignancies

Carcinoid syndrome

Reviewer: Hanni Gulwani, M.D. (see Reviewers page)
Revised: 22 December 2012, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.


● Occurs in 1% with carcinoid tumors, 20% with widespread metastases
● Elevated levels of 5 hydroxy-indoleacetic acid (5-HIAA), a metabolite, are found in blood and urine
● Normally liver deactivates vasoactive amines (serotonin, histamine, bradykinin, others) released from carcinoid tumors
● Clinical symptoms occur if liver metastases are present or if tumor venous blood flow bypasses the liver


● Vasomotor disturbances (cutaneous flushes, cyanosis of face and anterior chest, intermittent hypertension), palpitations, intestinal hypermotility (nausea, vomiting, diarrhea, cramps)
● Also asthmatic attacks with bronchospasm, fibrosclerosis of AV and tricuspid valves, elastotic sclerosis of mesenteric vessels causing ischemia, dermal sclerosis, hepatomegaly

Carcinoid heart disease

● Right sided focal or diffuse plaques of thickened valvular or mural endocardium that may extend to the great veins, coronary sinus, pulmonary trunk and main pulmonary arteries
● Tricuspid and pulmonic valves are usually affected by plaque formation
● Left heart and left sided valves are less frequently affected
● Endocardial fibrosis is a reaction to serotonin or kinin peptide exposure
● Plaques are composed of fibroblasts, myofibroblasts and smooth muscle cells embedded in a collagenous matrix, covered by a layer of endothelium
● No elastic tissue is present within the plaque

End of Small bowel (small intestine) > Other malignancies > Carcinoid syndrome

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).