Primary Rosai-Dorfman disease of the bone in a patient with history of breast cancer: appearance on 99mTc-MDP scintigraphy, CT, and X-ray

A 49-year-old woman with history of breast cancer presented with pain at the level of the left anterior proximal tibia. An x-ray of the tibia demonstrated a lytic cortical lesion that prompted a whole-body 99mTc-MDP bone scan. The bone scan revealed intense bone remodeling at the level of the tibial lytic lesion and in the cervical spine. CT demonstrated an expansile lesion eroding the vertebral bodies of C6 and C7 with a large soft tissue component. A biopsy of the cervical spine mass demonstrated features diagnostic of Rosai-Dorfman disease without evidence of neoplastic cells.