Carcinoid heart disease develops in more than one-third of patients with carcinoid syndrome. Pathologically, the cardiac valves become thickened because of fibrosis, and the tricuspid and pulmonic valves are affected to a greater extent than the mitral and aortic valves. Symptoms include:
- Tricuspid and pulmonic regurgitation.
- Pulmonary stenosis.
- Mitral and aortic insufficiency.
- Cardiac dysrhythmias.
Severe carcinoid heart disease is associated with reduced survival. (Refer to the Prognostic Factors section of this summary for more information.)
Site-Specific Clinical Features
The clinical features of GI carcinoids vary according to anatomical location and cell type.[5,12,24] Most carcinoids in the GI tract are located within 3 feet (~90 cm) of the ileocecal valve, with 50% found in the appendix. They are often detected fortuitously during surgery for another GI disorder or during emergency surgery for appendicitis, GI bleeding, or perforation.
Most gastric carcinoids are enterochromaffin-like (ECL)-cell carcinoids; rarely, other types may occur in the stomach. (Refer to Table 1 in the Cellular and Pathologic Classification of Gastrointestinal Carcinoid Tumors section of this summary for more information.)
Type I ECL-cell gastric carcinoids, the most common type, typically do not have clinical symptoms. They are often discovered during endoscopy for reflux, anemia, or other reasons; and are typically multifocal. Occurring most commonly in women (female-to-male ratio, 2.5:1) at a mean age of 63 years, achlorhydria may be present, and hypergastrinemia or evidence of antral G-cell hyperplasia is usually found.[5,24,27] These tumors are gastrin-driven and arise in a background of chronic atrophic gastritis of the corpus, usually because of autoimmune pernicious anemia but sometimes caused by Helicobacter pylori infection.
Type II ECL-cell carcinoids, the least common type of gastric carcinoids, occur at a mean age of 50 years with no gender predilection. The hypergastrinemia associated with MEN1-Zollinger-Ellison syndrome (ZES) is thought to promote the ECL-cell hyperplasia that leads to type II tumors.[27,28]
Type I and type II ECL-cell gastric carcinoids have been reported to metastasize in fewer than 10% of cases.[27,29] Type III gastric ECL-cell carcinoids, the second most common type of gastric carcinoid, occur mostly in men (male-to-female ratio, 2.8:1) at a mean age of 55 years. There are no neuroendocrine manifestations, and patients typically present with signs and symptoms related to an aggressive tumor.[5,30]
Comprising only 2% to 3% of GI NETs and discovered incidentally or because of symptoms from hormonal or peptide production, duodenal carcinoids may also arise in the periampullary region, obstruct the ampulla of Vater, and produce jaundice.[3,5,31] The age at presentation varies widely (range, 19-90 years; mean age, 53 years).[15,32]
The most common duodenal carcinoids are gastrin-producing G-cell tumors (~two thirds) followed by somatostatin-producing D-cell tumors (~one fifth), which rarely produce systemic manifestations of somatostatin excess.[5,31,33]