Lymphoproliferative disorder in an elderly rheumatoid arthritis patient after longterm oral methotrexate administration: A case report.

Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is frequently reported in the literature; however, its pathophysiology has not been fully elucidated to date. We herein describe a case of MTX-LPD that occurred after long-term treatment with oral MTX in a 67-year-old Japanese woman with rheumatoid arthritis (RA) who presented with generalized lymphadenopathy of the neck. The patient had been diagnosed with RA 24 years earlier, and had been on oral MTX for 20 years. The patient noticed a mass on her neck, which prompted a visit to our hospital. The mass was confirmed as diffuse large B-cell lymphoma by biopsy. MTX treatment was discontinued, which resulted in a reduction in the size of the mass and improvement of the patient's symptoms. Therefore, clinicians must be aware of MTX-LPD as a differential diagnosis for patients with rheumatological conditions on long-term MTX therapy presenting with signs and symptoms suggestive of lymphoma.