12 Foregut duplication cyst in duodenum with high grade dysplasia, A rare case report

Introduction/Objective Duplication cyst of gastrointestinal tract (GIT) are rare congenital abnormalities containing foregut derivatives like smooth muscle wall and enteric mucosa, found commonly on the mesenteric border of the intestine. The most common site of GIT involved is small intestine. Traditionally, there are 3 criteria that must be met to make a diagnosis of foregut duplication cyst: they must (1) be covered by a smooth muscle layer, (2) contain epithelium derived from the foregut, and (3) be attached to a portion of the foregut. We report a rare case of foregut duplication cyst with high grade dysplasia. Methods/Case Report A 35-year-old gentleman came to the Emergency Department of our hospital with epigastric and right upper quadrant abdominal pain. CT imaging demonstrated a 13 x 11 x 10 cm complex cystic lesion in the right abdomen. The superior aspect of the cyst abutted the distal stomach. Histopathological examination revealed a soft to slightly firm, rubbery, circumscribed mass measuring 7.5 x 5.5 x 5.2 cm. On sectioning the mass appeared to be a unilocular cyst containing yellow mucoid fluid with smooth inner linings. On microscopy, the cyst had ganglionated smooth muscle wall with areas of low grade dysplasia and focal area of high-grade dysplastic mucinous lining. There was extensive extravasated mucin within the wall. Additionally, there was ectopic gastric and pancreatic tissue within the wall of the cyst. These findings are compatible with a mucinous neoplasm arising in a foregut duplication cyst (arising from duodenum). The diagnosis was made as Mucinous neoplasm with focal high-grade dysplasia arising in a duplication cyst. A cytokeratin AE1/AE3 immunostaining supported the above diagnosis. Results N/A Conclusion Our case presents a unique duplication cyst with low and high grade dysplasia. Foregut duplication cysts of the duodenum may present a diagnostic dilemma and should be included in the differential diagnosis. Currently no clear guidelines are available for diagnostic approaches, malignancy risk, and treatment options for duplication cysts in adults. More cases need to be reported in order to build standard treatment guidelines and determine prognostic criteria.