Cytologic features of pancreatobiliary neoplasm of duodenum

Abstract Small intestinal adenomas are uncommon. Majority of these occur in the region of the ampulla of Vater. Adenomas of the ampulla can be further subdivided into two types—intestinal and pancreatobiliary. While intestinal adenomas are more frequent, pancreatobiliary adenomas are rare. There is limited literature regarding the role of endoscopic ultrasound‐guided fine needle aspiration (EUS‐FNA) in the diagnosis of ampullary/peri‐ampullary neoplasms. Here, we describe the cytologic features of a pancreatobiliary neoplasm of the duodenum that was sampled by EUS‐FNA. The aspirate was cellular and revealed cells with moderately abundant oncocytic cytoplasm. The nuclei were round with fine chromatin and focally prominent nucleoli. Although the concurrent biopsy showed no high‐grade dysplasia or invasive carcinoma, the EUS and imaging findings were highly suspicious for invasion. A broad differential diagnosis is under consideration for a duodenal mass that encompasses neoplasms of the biliary tract, pancreas, duodenum, and ampulla of Vater. To our knowledge, cytologic features of a pancreatobiliary neoplasm of the duodenum have not been previously reported. Our case highlights the features seen on cytology with histologic correlation in the hopes of elucidating features to better characterize these lesions.