Primary Pancreatic Mantle Cell Lymphoma Diagnosed via Endoscopic Ultrasound-Guided Fine-Needle Aspiration.

Primary pancreatic lymphomas (PPLs) are rare, and the histological classification of these tumors is difficult. To accurately diagnose and determine the appropriate treatment for PPLs, sufficient sample amounts are necessary. Here, we report a 73-year-old man with a primary pancreatic mantle cell lymphoma. Histological samples were obtained via endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). The tumor cells predominantly composed of atypical small to medium round cells, with diffuse immunoreactivity of CD20 and cyclin D1. In addition, immunoglobulin gene H chain rearrangement was detected. The patient underwent chemotherapy, resulting in complete remission. Eight years after the initiation of chemotherapy, the patient was still alive. EUS-FNA could be a useful and safe diagnostic modality for PPLs by providing enough samples for testing.