Fluorine-18-deoxyglucose positron emission tomography/computed tomography ([18F]FDG PET/CT) has been shown to be superior to other conventional imaging modalities in the detection of extra-nodal lymphomatous localizations. Especially in neurolymphomatosis which is rarely encountered in high-grade lymphomas. We report a case of a woman diagnosed with non-Hodgkin lymphoma, whose initial staging with [18F]FDG PET/CT showed increased [18F]FDG uptake along the brachial and sacral plexuses. [18F]FDG PET/CT remains the most appropriate diagnostic tool in these cases, whose prognosis is often poor.