Tubulovillous adenoma of the duodenum: A new etiology for flushing and urinary 5-HIAA elevation

We report the case of a 45-year-old woman who presented with episodic flushing in association with elevated urinary levels of 5-hydroxyindoleacetic acid. After an extensive unrevealing search for a carcinoid tumor was performed, esophagogastroduodenoscopy was done and revealed a sessile tubulovillous adenoma in the second portion of the duodenum. The adenoma was successfully removed surgically. Postoperatively, urinary 5- hydroxyindoleacetic acid levels returned to normal, and flushing disappeared. Immunohistochemical staining demonstrated the presence of serotonin in the tubulovillous adenoma but not in the surrounding normal mucosa. This is the first report of a patient with a neoplasm other than a carcinoid tumor, a tubulovillous adenoma, presenting with symptoms of flushing in association with elevated urinary levels of 5-hydroxyindoleacetic acid. When a carcinoid tumor cannot be found in a patient in the presence of appropriate symptoms and elevated urinary 5-hydroxyindoleacetic levels, other disorders known to present in this fashion should be searched for.