For gastrointestinal tract carcinoids, the vasoactive peptides are inactivated if they pass through the portal vein to the liver and there may be no systemic symptoms. Symptoms develop if the carcinoid tumor is malignant and metastasizes to the liver.
Clinical features of carcinoid syndrome:
(1) episodic flushing involving the face, neck and/or upper trunk, which may be accompanied by increased salivation, lacrimation, sweating and/or swelling
(2) gastrointestinal hypermotility
(2a) abdominal pain
(2b) chronic watery diarrhea
(2c) steatorrhea
(3) wheezing progressing to bronchospasm
(4) heart disease, usually right sided
(3a) endocardial fibrosis
(3b) tricuspid valve regurgitation
(3c) pulmonary valve stenosis
(3d) heart failure
(5) telangiectasia
(6) hypotension or hypertension
(7) tachycardia and palpitations
(8) pellagra skin rash (niacin deficiency)
(9) fibrotic reactions (retroperitoneal, Peyronie's disease, mesenteric, vascular)
(10) increased urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA)
A "carcinoid crisis" refers to a severe reaction which may include severe hypotension, bronchospasm with respiratory arrest, chest pain, cardiac arrhythmia and/or encephalopathy. This may occur following surgical manipulation of the tumor or following injection of certain drugs (catecholamines, pentagastrin, etc.).
