S1613 Intrapancreatic Accessory Spleen: A Concerning Mass With Reassuring Pathology

Abstract

Introduction: Intrapancreatic accessory spleen (IPAS) is a congenital focus of healthy splenic tissue present outside of the splenic parenchyma. There are numerous locations for IPAS and they are usually found incidentally. The location of ectopic splenic tissue is important as it can often mimc as a neoplasm, most commonly neuroendocrine tumor (NET) due to similar imaging characteristics on nuclear imaging and CT scan. We report on the finding of an IPAS in the tail of the pancreas for which fine needle aspiration was performed. Case Description/Methods: A 66-year-old man with past medical history of prostate cancer managed with brachytherapy presented to his urologist for workup of persistently elevated prostate specific antigen. He underwent a nuclear medicine whole body scan which revealed uptake in the pancreatic tail for which follow up computed tomography (CT) was recommended. The patient was seen by the gastroenterology and a CT scan was obtained. CT revealed a 4cm x 3cm isoenhancing mass in the tail of the pancreas without invasion to surrounding structures nor communication with the pancreatic ducts. No lymphadenopathy was noted. The patient subsequently underwent endoscopic ultrasound (EUS) with fine needle aspiration (FNA) of the mass. EUS revealed a hypoechoic, oval, mass-like structure in the distal pancreatic tail measuring ∼20mm x 20mm in maximal cross-sectional diameter. FNA of the mass was performed. Cytopathology of the specimen revealed small mature lymphocytes and vessels suggestive of IPAS. The patient remained asymptomatic through the duration of the workup. Discussion: All enhancing pancreatic lesions require further workup to rule out malignancy. Typically, patients undergo scintigraphy for further evaluation or FNA biopsy via EUS for confirmation. Currently, there are no established serum markers or radiographic findings with adequate specificity for diagnosing IPAS. It is important to recognize the impact of incidental findings as they frequently require further testing and often result in procedural intervention. IPAS is often confused with NET, frequently necessitating tissue sampling. While the prevalence of intrapancreatic accessory spleen is higher than initially thought, contrary to NET it carries no inherent risk unless its location compromises vital structures. This highlights the importance of recognizing this anomaly.Figure 1.: Panel A: CT Image including mass in pancreas, Panel B: EUS with FNA of mass Panel C: H&E stain of pathology specimen.