Abstract: The authors report a case of extramedullary plasmacytoma in multiple lymph nodes of whole body of ¹⁸F-FDG PET/CT imaging. The characteristics of the disease were analyzed from the clinical symptoms, laboratory examination, pathological examination, and ¹⁸F-FDG PET/CT imaging. The characteristics of extramedullary plasmacytoma and differential diagnosis were analyzed retrospectively. Imaging results of ¹⁸F-FDG PET/CT showed lymph nodes are swollen at multiple sites throughout the body, and ¹⁸F-FDG PET/CT imaging showed noticeable hypermetabolism of FDG in these places with a SUV_max14.2. ¹⁸F-FDG PET/CT imaging can provide a reference for the diagnosis of extramedullary plasmacytoma in multiple lymph nodes of whole body.