Pancreatic neuroendocrine tumor trapped in a cyst

Abstract

Pancreatic neuroendocrine tumor (Pan NET) accounts for only 1–2% of pancreatic neoplasms and <1% of tumors present as cystic lesions. A diagnosis of cystic tumor in the pancreas can be very challenging and confusing. Endoscopic ultrasound (USG) and fine needle aspiration (FNA) of these cystic lesions can help the clinician to narrow down the differential diagnosis. A multidisciplinary approach is warranted for a definitive diagnosis and optimal treatment. Here, we present to you a very rare case of Pan NET presenting as a cystic mass. A 65-year-old man was admitted with a history of abdominal pain. Laboratory tests showed increased levels of serum amylase, and other biochemical tests were normal. The patient underwent transabdominal USG and computed tomography (CT). CT showed well-defined cystic lesion in the proximal body of the pancreas. Endoscopic guided FNA (EUS-FNA) using 22 gauges was done. Cytological examination demonstrated clusters and sheets of plasmacytoid cells. EUS core needle biopsy was done which showed loose clusters of cells with fine uniformly distributed chromatin that stained positively for insulinoma associated protein-1 which was suggestive of a Pan NET. The differential diagnosis of cystic lesions in the pancreas is very difficult with conventional radiology such as CT and magnetic resonance imaging. Cytology is helpful for a pre-operative diagnosis of cystic Pan NET. A diagnosis of Pan NET in a pancreatic biopsy or FNA with limited and suboptimal material is often challenging. This unusual case highlights the importance of pre-operative workup of EUS followed by FNAC in cystic pancreatic lesions.