Vascular FDG Uptake on PET/CT in Patients Receiving Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies structured as immunoglobulin G1 and immunoglobulin G4, employed in the treatment of various cancers by targeting specific molecules, including programmed cell death receptor-1 (PD-1), programmed cell death ligand-1 (PD-L1), and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4). 1Currently, they are utilised independently, in conjunction with traditional chemotherapies, or in combination with one another (against PD-1 or anti PDL-1 and CTLA-4) for the treatment of various malignancies. 2Alongside offering considerable survival benefits in numerous cancer types, numerous immune-related adverse events (irAEs) such as pneumonitis, colitis, hepatitis, hypophysitis, thyroiditis, nephritis, and rash have been documented. 3,4In addition to these clearly delineated irAEs, numerous case reports indicate that these medications can induce vasculitis with diverse presentations, encompassing both large-vessel vasculitis and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis.Nonetheless, there is no definitive consensus about the mechanism of ICI-related vasculitis. 5