EUS-FNA diagnosis of pancreatic serous cystadenoma with the aid of cell blocks and α-inhibin immunochemistry: A case series.

Serous cystadenoma (SCA) is an uncommon benign pancreatic neoplasm that is most often managed conservatively with follow-up rather than surgical excision. Therefore, to avoid the serious complications of pancreatic surgery, SCA should be diagnosed accurately at the preoperative level. Preoperative SCA diagnosis requires a multimodal diagnostic approach that includes imaging, cystic fluid biochemical analysis and/or endoscopic ultrasound fine-needle aspiration (EUS-FNA). In this brief report, we describe six EUS-FNA cases from five patients that were reported as "benign, consistent with serous cystadenoma". Samples were hypocellular, composed of loose clusters and single cuboidal, bland-looking cells among epithelial sheets representing gastrointestinal contamination. Cell blocks were prepared and all six FNA cases revealed cuboidal cells with a positive α-inhibin immunophenotype, consistent with a diagnosis of SCA. As EUS-FNAs of SCA commonly result in non-diagnostic interpretations, cell block preparations with subsequent immunochemistry can increase their diagnostic accuracy and guide patient management.