Extranodal Rosai-Dorfman disease as solitary lesion of the tibia in a 56-year-old woman.

We report the case of a 56-year-old woman who had severe leg pain and whose radiographs initially suggested metastatic carcinoma, lymphoma, osteogenic sarcoma, or adamantinoma. Results of multiple biopsies confirmed a diagnosis of Rosai-Dorfman disease, which typically presents in children and young adults (mean age at onset, 20 years).