Other Iatrogenic Immunodeficiency-associated Lymphoproliferative Disorder Presenting as Primary Bone Lymphoma in a Patient with Rheumatoid Arthritis.

Primary bone lymphoma (PBL) is a rare disorder. We herein present a case of other iatrogenic immunodeficiency-associated lymphoproliferative disorder (OIIA-LPD) presenting as PBL. A 63-year-old woman was diagnosed with rheumatoid arthritis and had been treated with methotrexate for seven years. Two months before admission, she suffered from pain in the limbs. Magnetic resonance imaging revealed multiple irregular lesions in the bones of the limbs, which showed an uptake of (18)F-FDG on positron emission tomography. A biopsy of the right radius revealed diffuse large B-cell lymphoma, leading to the diagnosis of OIIA-LPD. She received rituximab-containing regimens resulting in a complete response.