3224 A Rare Case of Duodenal Adenocarcinoma in Situ Arising in the Background of Villous Adenoma

Abstract

INTRODUCTION: Villous adenomas (VA) of the small bowel are the most common benign periampullary neoplasms with the highest potential for malignant transformation to adenocarcinoma. Adenocarcinoma of the small bowel accounts for only 1% of all gastrointestinal malignancies and duodenal adenocarcinoma (DA) constitutes approximately half of these cases. Although a rare and aggressive cancer, DA has the more favorable outcomes than other periampullary malignancies. Hence, it is important to understand the pathogenesis of DA as well as pre-malignant lesions such as VA. We present a male with long standing history of iron deficiency anemia found to have a duodenal mass identified as adenocarcinoma in situ arising in the background of VA. CASE DESCRIPTION/METHODS: A 73-year-old male, with a medical history of hypertension, Hepatitis C status post treatment and iron-deficiency anemia was referred for anemia with a hemoglobin of 6.2. He reported recent fatigue with no dyspnea, chest pain, melena, hematochezia or hematemesis. Colonoscopy 1-year ago was significant for a tubular adenoma with recommendation to repeat procedure in 5 years. Patient was transfused 1 unit of red blood cells on admission and started on oral iron supplement. He remained hemodynamically stable. Push enteroscopy showed a circumferential mass in the 3rd portion of the duodenum without obstruction. Biopsy noted adenocarcinoma in situ arising in the background of villous adenoma. Patient was evaluated by the surgical team with a plan for resection and subsequent follow-up with an Oncologist. DISCUSSION: VA accounts for only 1% of all duodenal tumors. Given their rarity, pathogenesis and rate of transformation to adenocarcinoma is unclear. Symptoms associated with VA depends on their location in the duodenum and can range from vague abdominal complains to biliary or small bowel obstruction, pancreatitis or iron deficiency anemia. Iron deficiency anemia in our patient was likely secondary to impaired absorption of iron in the duodenum due to the mass. Duodenal adenomas are associated with an increased risk of colonic adenomas, similar to our patient given his history of tubular adenoma in the colon. Hence, concomitant colonoscopy is warranted for early diagnosis of potentially pre-malignant colonic lesions in patients with duodenal adenomas. With regards to treatment, complete resection of VA is recommended given their high risk of malignant transformation.