Solid Pseudopapillary Tumor of the Pancreas: An Unusual Cause of Abdominal Pain.

Solid-pseudopapillary neoplasm (SPN) of the pancreas is a rare tumor that accounts for less than one percent of pancreatic tumors. The diagnosis could be challenging as SPN tend to manifest with nonspecific abdominal symptoms, variable radiological features, and inconsistent morphology. The cellular origin of SPN is unclear and might involve ductal, acinar and endocrine stem cells.  We report a rare case of a 27-year-old female who presented with intermittent abdominal pain for two years, associated with a decrease in appetite. Her medical history was significant for abdominoplasty five years ago. Vital signs were stable. Physical examination revealed mild epigastric tenderness. Laboratory tests were unremarkable. Contrast computed tomography (CT) scan of the abdomen showed a 2 x 2 cm indeterminate pancreatic tail lesion. An endoscopic ultrasound (EUS) disclosed a 2.1 x 1.8 cm hypoechoic mass in the tail of the pancreas.Trans-gastric fine needle aspiration was obtained to show clusters of uniform neoplastic cells with abundant cytoplasm and oval bean-shaped nuclei. Immunohistochemical stains were positive for beta-catenin, Vimentin, CD10, CD56, cytokeratin-7 (Ck7), Cyclin D1, and negative for chromogranin, epithelial-cadherin (E cadherin) which was consistent with a pseudopapillary tumor. The patient underwent a robotic assisted en-bloc distal pancreatectomy and splenectomy. There were no intra-abdominal metastases. SPN is a rare tumor characterized by a specific immunohistological pattern which makes it highly distinct from other pancreatic neoplasms particularly neuroendocrine tumors, acinar carcinomas, and carcinoids. It is important to differentiate SPN from other pancreatic neoplasms because it is characterized as low potential for malignancy and a favorable prognosis after resection, with a five-year survival rate approaching 85%-95%.