Small intestine & ampulla
Other malignancies
Carcinoid syndrome
Author: Hanni Gulwani, M.B.B.S.
Last author update: 1 August 2012
Last staff update: 19 November 2020
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: Carcinoid syndrome[TI] small bowel
Cite this page: Gulwani H. Carcinoid syndrome. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/smallbowelcarcinoidsyndrome.html. Accessed April 23rd, 2024.
Definition / general
- Occurs in 1% with carcinoid tumors, 20% with widespread metastases
- Elevated levels of 5-hydroxyindoleacetic 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
Symptoms
- 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
