Clinical Value of ¹⁸F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Neuroendocrine Neoplasms: A Case Report and Literature Review

Neuroendocrine neoplasms (NENs) are rare and heterogeneous tumors in which functional imaging plays a central role in diagnosis, staging, and prognostic stratification. While somatostatin receptor (SSRs)-based imaging remains the standard for well-differentiated tumors, ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) provides complementary information on tumor metabolism and aggressiveness. We present the case of a 52-year-old male diagnosed in 2013 with a low-grade pancreatic neuroendocrine tumor who underwent surgical resection followed by multiple reinterventions due to local progression and mesenteric metastases. Serial SSR PET/CT studies demonstrated high receptor expression in mesenteric lesions. However, subsequent ¹⁸F-FDG-PET/CT revealed a hypermetabolic mesenteric nodal conglomerate, suggesting heterogeneous metabolic behavior and possible tumor dedifferentiation. This case highlights the clinical value of ¹⁸F-FDG-PET/CT in low-grade NENs, particularly for assessing disease progression, by providing prognostic information beyond histological grading alone. ¹⁸F-FDG-PET/CT may identify aggressive tumor components not evident on receptor-based imaging, supporting its role as a complementary tool in selected patients.