18F-FDG PET/CT of Widespread Rosai-Dorfman Disease

We present a rare case of Rosai-Dorfman disease who was sent for whole-body 18F-FDG PET/CT to know the exact extent of involvement. PET/CT revealed extensive nodal and extranodal involvement from head to toe including osteolytic lesions in metacarpals, metatarsals, and phalanges. It is important to know the exact extent of the disease as this may alter the patient management.