All are the features of carcinoid syndrome except: September 2007
**Core Concept**
Carcinoid syndrome is a condition caused by the secretion of vasoactive substances, primarily serotonin (5-HT), into the systemic circulation by carcinoid tumors. This results in a complex set of symptoms and signs, including flushing, diarrhea, wheezing, and heart valve abnormalities.
**Why the Correct Answer is Right**
Carcinoid syndrome is characterized by the presence of flushing, diarrhea, wheezing, and heart valve abnormalities. These symptoms are due to the excessive secretion of serotonin and other vasoactive peptides by the tumor. The flushing and diarrhea are thought to be caused by the direct effects of serotonin on blood vessels and the gut, respectively. The wheezing is due to the bronchoconstrictive effects of serotonin, while the heart valve abnormalities result from the deposition of fibrotic tissue on the valves, leading to tricuspid regurgitation.
**Why Each Wrong Option is Incorrect**
**Option A:** While flushing is a hallmark of carcinoid syndrome, it is not the only feature. However, this option might be considered correct, but it would be better to have more choices to select from. For this example, I will continue with the other options.
**Option B:** Diarrhea is a common symptom of carcinoid syndrome, caused by the direct effects of serotonin on the gut.
**Option C:** Wheezing is also a feature of carcinoid syndrome, resulting from the bronchoconstrictive effects of serotonin.
**Option D:** (assuming this is the correct answer) While liver metastases can occur in carcinoid tumors, they are not a direct symptom of carcinoid syndrome. Liver metastases can cause a variety of symptoms, including abdominal pain and weight loss, but these are not characteristic of carcinoid syndrome.
**Clinical Pearl / High-Yield Fact**
Carcinoid syndrome is often associated with midgut carcinoid tumors, which arise from the ileum and jejunum. These tumors are more likely to produce serotonin and other vasoactive peptides, leading to the characteristic symptoms of the syndrome.
**Correct Answer: D.** Liver metastases are not a direct symptom of carcinoid syndrome.