Gastrointestinal Stromal Tumor of the Ampulla of Vater: A Narrative Review.

Background: Gastrointestinal stromal tumor (GIST) of the ampulla of Vater is a rare occurrence. To the best of our knowledge, there has been no published review on this rare tumor in the English literature so far.

Summary: In this review, we will discuss all the reported details of the published cases, including demography, clinical presentation, imaging, gross pathology and histopathology, immunohistochemical findings, treatment modalities, and outcome of cases with the diagnosis GIST from the ampulla of Vater in the last 20 years.

Key Message: Twenty-five cases of GIST in the ampulla of Vater have been reported in the last 20 years in the English literature. GIST in the ampulla of Vater are usually small tumors (<5 cm) in middle-age patients. The majority of the patients present with lower GI bleeding and abdominal pain. Imaging findings are not characteristic, and most of the patients without biopsy and with no histologic diagnosis were operated with the primary impression of adenocarcinoma, neuroendocrine tumor, and GIST. Perioperative tissue biopsy has been accurate in <70% of the cases. The majority of the reported cases of GISTs in the ampulla of Vater have been low risk with spindle-cell morphology, low mitotic figures, and minimal atypia; reactive for C-KIT and DOG-1; and nonreactive for SMA, desmin, and S100. In the majority of the cases, duodenectomy with or without Whipple's operation has been performed, and most of the cases showed good prognosis.