18F-FDG PET/CT assists the diagnosis of primary pancreatic lymphoma: Two case reports and literature review

Abstract

Primary pancreatic lymphoma (PPL) is a rare malignancy, which is defined as a mass centered in pancreas with involvement of contiguous lymph nodes and distant spread may exist. Accurate diagnosis of PPL prior to pathological confirmation remains challenging, underscoring the critical significance of preoperative imaging assessments. This case report collected two instances of PPL that underwent initial evaluation via 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) between August 2021 and July 2022. Correspondingly, pertinent literature encompassing 18F-FDG PET/CT data related to PPL was meticulously reviewed. Including our aforementioned pair of cases, a cumulative total of 25 instances of PPL were assembled. The distinctive profile of 18F-FDG PET/CT images of PPL predominantly manifests as hypermetabolic lesions with diminished density. Primarily characterized by singular lesions and comparatively substantial volumetric dimensions, a total of eleven cases revealed contiguous lymph node engagement, with five instances displaying distant dissemination encompassing lymph nodes in multiple locations. Amongst these, ten patients underwent sequential 18F-FDG PET/CT follow-up post-intervention. In comparison to pancreatic carcinoma, PPL lesions exhibited heightened hypermetabolism, augmented volumetric proportions, and distinct patterns of distant metastasis. This study indicates that the pivotal role of 18F-FDG PET/CT in the diagnosis and assessment of therapeutic efficacy in PPL is unequivocal. Combined with the clinical attributes of patients, the integration of 18F-FDG PET/CT augments the differential diagnostic capacity differentiating PPL from pancreatic carcinoma.