2161 A Rare Case of Pancreatic Lymphoepithelial Cyst

Abstract

INTRODUCTION: Pancreatic lymphoepithelial cyst (LEC) is a rare, benign collection of keratinizing squamous epithelial cells encapsulated by lymphoid tissue. Because of its limited data and nonspecific features that can mimic malignant lesions, LECs can lead to unnecessary operations. Here we describe a rare case of pancreatic LEC. CASE DESCRIPTION/METHODS: A 62-year-old male with a known pancreatic mass presented with abdominal pain. CT scan showed a 36 × 52 mm mass in the pancreatic head with no pancreatic ductal dilation or retroperitoneal lymphadenopathy (Figure 1), which increased in size compared to previous imaging. Endoscopic ultrasound (EUS) showed a well-defined, avascular 49 × 29 mm heterogenous hypoechoic mass by the pancreatic neck without pancreatic ductal dilation (Figure 2). Subsequent EUS-guided fine needle aspiration (FNA) revealed rare fragments of benign-appearing squamous epithelium in a background of keratin debris, cyst contents, and scattered lymphocytes, consistent with a lymphoepithelial cyst (Figure 3). DISCUSSION: Pancreatic LEC is an extremely rare lesion that comprises of only 0.5% of all pancreatic cysts. It occurs in males 50-60 years of age as an incidental finding, albeit patients may present with abdominal pain and nausea. A majority of the LECs are round, anechoic or hypoechoic, exophytic complex cystic lesions with enhancing septa or rim. However, these features can overlap with other pancreatic lesions such as intraductal papillary mucosal neoplasms that have malignant potential, leading to unnecessary surgical intervention. Thus EUS-FNA has become the mainstay for diagnosing pancreatic LECs, which show an outer layer of lymphoid tissue and an inner layer of mature squamous epithelium without atypia. Given the slow growing and benign nature, conservative management and observation is adequate for pancreatic LECs with excellent long-term outcome. With increasing number of imaging ordered by clinicians, it is anticipated that there will be a greater number of incidental pancreatic LECs detected, which in turn can increase the number of unnecessary procedures. EUS-FNA should be utilized more frequently to help distinguish benign pancreatic LECs from premalignant or malignant lesions to avoid surgery. It is important for clinicians to become more familiar with the cytopathological characteristics of pancreatic LECs, and this case highlights the importance of EUS-FNA in accurately diagnosing a rare pancreatic LEC.