Clinical features and images of malignant lymphoma localized in the pancreatic head to differentiate from pancreatic ductal adenocarcinoma: a case series study

Pathological examination by endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) has been reported to be useful in diagnosing pancreatic malignant lymphoma (ML), but some ML cases are difficult to be differentiated from pancreatic ductal adenocarcinoma (PDAC). This retrospective study included 8 patients diagnosed with ML that had a pancreatic-head lesion at initial diagnosis and 46 patients with resected PDAC in the pancreatic head between April 2006 and October 2021 at our institute. ML and PDAC were compared in terms of patients' clinical features and imaging examinations. The median tumor size was larger in ML than in PDAC (45.8 [24-64] vs. 23.9 [8-44] mm), but the median diameter of the caudal main pancreatic duct (MPD) was larger in PDAC (2.5 [1.0-3.5] vs. 7.1 [2.5-11.8] mm), both showing significant differences between these malignancies (both, P