Abstract
RATIONALE: Pancreatic lymphoepithelial cyst (PLEC) is a rare benign pancreatic cystic lesion that poses considerable diagnostic challenges owing to its overlapping clinical and imaging features with malignant neoplasms. Misdiagnosis frequently results in unnecessary surgical interventions. This case report aims to elucidate specific clinical and radiological characteristics essential for the accurate diagnosis of PLEC. PATIENT CONCERNS: A male patient presented with abdominal pain. Laboratory tests revealed elevated serum carbohydrate antigen 19-9 (CA19-9) levels. An abdominal computed tomography (CT) scan identified a cystic mass in the head and body of the pancreas. DIAGNOSES: The patient underwent a partial pancreatectomy and splenectomy, followed by histopathological biopsy, which confirmed the diagnosis of PLEC. INTERVENTIONS: Following postoperative PLEC diagnosis, the patient was placed under regular surveillance, including abdominal CT scans and serum CA19-9 monitoring. OUTCOMES: The patient underwent partial pancreatectomy and splenectomy without complications. Abdominal pain completely resolved by postoperative day 18. By day 30 of follow-up, CA19-9 levels had decreased to 9 U/L. Subsequent evaluations at 6 months, including abdominal CT and tumor marker assessments, confirmed sustained remission without evidence of recurrence, indicating an excellent clinical outcome. LESSONS: PLEC, a rare benign lesion, often mimics malignancy, potentially leading to unnecessary radical surgeries. Diagnostic hallmarks include its tendency to present as an exophytic cystic mass in middle-aged men; CT features demonstrating cyst fluid density exceeding that of simple or mucinous cysts with thin, mildly enhancing walls; and pathognomonic magnetic resonance imaging findings of T2-hyperintense subcapsular nodules exhibiting restricted diffusion in a noninfiltrative, wall-apposed pattern without ductal communication. Markedly elevated CA19-9 levels should not preclude PLEC. When this constellation of features is present, PLEC should be considered in the differential diagnosis.