Unusual Sole Extramedullary Diffuse Kidney Involvement in Multiple Myeloma Initial Workup Using 2-[ 18 F]FDG-PET/CT Imaging.

2-[ 18 F]fluorodeoxyglucose-positron emission tomography with computed tomography (2-[ 18 F]FDG-PET/CT) in multiple myeloma (MM) allows the detection of extramedullary disease (EMD), which is scarce at initial workup. We report here for the first time uncommon 2-[ 18 F]FDG-PET/CT imaging results of a 63-year-old woman with newly diagnosed MM and sole diffuse kidney EMD revealed by a significantly increased renal volume and intense/diffuse bilateral renal cortical uptake without visualization of the urinary excretory cavities then confirmed by kidney biopsy. This case highlights the possibility of a diffuse organ involvement different from the typical imaging pattern of nodular plasmacytoma lesions in soft tissues.