A 60-year-old man presents to your office with facial flushing and abdominal cramps and diarrhea. The workup reveals an elevated level of urinary 5-hydroxyindoleacetic acid (5-HIAA), and subsequently, elevated levels of 5-HIAA in a 24-hour urine collection. What is the most likely diagnosis?
A) Zollinger-Ellison syndrome
B) Cushing's syndrome
C) Malignant carcinoid syndrome
D) Vipoma
E) Glucagonoma

Question

Quizplus · Accepted Answer

The elevated level of urinary 5-hydroxyindoleacetic acid (5-HIAA), which is a breakdown product of serotonin, along with symptoms of facial flushing, abdominal cramps, and diarrhea, are characteristic of malignant carcinoid syndrome. This syndrome is caused by carcinoid tumors, which most commonly originate in the gastrointestinal tract.

A 60-Year-Old Man Presents to Your Office with Facial Flushing