The role of 18F-FDG PET/CT in primary cutaneous lymphoma: an educational review

Introduction Primary cutaneous lymphoma (PCL) is a cutaneous non-Hodgkin’s lymphoma that originates in the skin and lacks extracutaneous spread upon initial diagnosis. The clinical management of secondary cutaneous lymphomas is different from that of PCLs, and earlier detection is associated with better prognosis. Accurate staging is necessary to determine the extent of disease and to choose the appropriate treatment. The aim of this review is to investigate the current and potential roles of 18F- fluorodeoxyglucose positron emission tomography–computed tomography (18F-FDG PET/CT) in the diagnosis, staging, and monitoring of PCLs. Methods A focused review of the scientific literature was performed using inclusion criteria to filter results pertaining to human clinical studies performed between 2015 and 2021 that analyzed cutaneous PCL lesions on 18F PET/CT imaging. Results & Conclusion A review of 9 clinical studies published after 2015 concluded that 18F-FDG PET/CT is highly sensitive and specific for aggressive PCLs and proved valuable for identifying extracutaneous disease. These studies found 18F-FDG PET/CT highly useful for guiding lymph node biopsy and that imaging results influenced therapeutic decision in many cases. These studies also predominantly concluded that 18F-FDG PET/CT is more sensitive than computed tomography (CT) alone for detection of subcutaneous PCL lesions. Routine revision of nonattenuation-corrected (NAC) PET images may improve the sensitivity of 18F-FDG PET/CT for detection of indolent cutaneous lesions and may expand the potential uses of 18F-FDG PET/CT in the clinic. Furthermore, calculating a global disease score from 18F-FDG PET/CT at every follow-up visit may simplify assessment of disease progression in the early clinical stages, as well as predict the prognosis of disease in patients with PCL.