Lymphoepithelial Cyst of the Pancreas Presenting as a Solid Mass: A Surgery Prevented by Endoscopic Ultrasound

Abstract

Introduction: Pancreatic cysts can be divided into two types: true cysts with an epithelial lining and pseudocysts. Lymphoepithelial cysts (LECs) are true pancreatic cysts that are benign and rare. LECs have variable appearances on imaging studies, sometimes masquerading as a suspicious solid mass, leading to unnecessary surgical resection. Endoscopic ultrasonography (EUS) with fine-needle aspiration (FNA) can diagnose LECs accurately. We report a rare case of LEC seen as a solid pancreatic mass on MRI but later diagnosed by EUS-FNA. This prevented unwarranted resection of a benign lesion. Case Report: A 55-year-old obese male presented with vague right upper quadrant abdominal pain radiating to the left. He denied any fever, nausea, vomiting, weight loss, or change in bowel habits. He had a history of hypertension, coronary artery disease and dyslipidemia. He was a chronic smoker but denied alcohol or illicit drug use. Family history was significant for colon cancer in a brother. Physical exam was unremarkable and liver function tests were normal. A contrast-enhanced CT scan of the abdomen showed a well-defined, partially cystic, exophytic mass measuring 3.2 cm in the distal pancreatic body. On MRI with contrast, the exophytic mass appeared solid with mild enhancement. The morphology was atypical but no overt invasion of vessels or lymphadenopathy was noted. Differential diagnosis included neoplasms like adenocarcinoma, intraductal papillary mucinous neoplasm, acinar cell tumor or a benign pseudocyst. CEA and CA 19-9 were normal. A EUS with FNA was performed. Cytology revealed benign squamous cells, scattered lymphocytes, cholesterol crystals and debris, consistent with a diagnosis of LEC. A decision was made to observe the patient with serial imaging due to the benign nature of the lesion. Interestingly, a second look at the MRI revealed low signals in T2 and intermediate signals in T1-weighted images. A fat-suppressed T1-weighted image showed relatively high signals because of the keratin content of the cyst, making it appear solid. This characteristic feature of LECs should improve the diagnostic utility of MRI in these cases. Discussion: LECs of the pancreas are rare, benign and predominantly occur in middle-aged men. They are usually incidental with uncertain pathogenesis. Some present with nausea, vomiting, diarrhea or abdominal pain. LECs can be diagnosed on MRI with fat-suppressed T1 images. Definitive diagnosis using EUS-guided FNA can prevent unwarranted surgical resection of this benign lesion as illustrated in this case.