Rosai-Dorfman disease (RDD) or "sinus histiocytosis with massive lymphadenopathy" is a rare lymphoproliferative disorder of unknown etiology. The disease usually presents with painless lymphadenopathy with occasional extranodal involvement in various organs. We report a case of a 36-year-old man with a history of non-Hodgkin lymphoma (NHL), who recently presented with inguinal lymphadenopathy. Following the diagnosis of RDD on lymph node biopsy, he developed symptoms of spinal cord compression due to a mass lesion discovered at T6-7 vertebral level. 18F-Fluorodeoxyglucose (18FDG) positron emission tomography (PET-CT) revealed extensive disease with lung, renal and bone involvement. The patient received a short course of steroid therapy for cord compression findings and 2-chlorodeoxyadenosine (2-CdA) treatment was initiated for long-term disease control. He had a dramatic sustained response to treatment with six courses of 2-CdA. These results suggest that 2-CdA can be an effective treatment of choice and positron emission tomography with 18FDG can be used for determining the extent of disease and for follow-up in RDD.