A 45-year-old female presents with episodic flushing, watery diarrhea, and bronchospasm. Echocardiography reveals tricuspid regurgitation. Urinary 24-hour excretion of 5-hydroxyindoleacetic acid (5-HIAA) is markedly elevated. What is the primary diagnosis?
Answer and explanation
Correct answer: A. Metastatic carcinoid neuroendocrine tumor (carcinoid syndrome)
- Step 1: Carcinoid syndrome is caused by neuroendocrine tumor secretion of vasoactive amines (serotonin, bradykinin, prostaglandins).
- Step 2: Primary intestinal carcinoids only produce systemic symptoms after metastasizing to the liver, as hepatic monoamine oxidase previously inactivated portal secretions.
- Step 3: Elevated 24-hour urinary 5-HIAA confirms excess serotonin metabolism.
Answer
Metastatic carcinoid neuroendocrine tumor (carcinoid syndrome).
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