A Case of Methotrexate-Associated Lymphoproliferative Disorder That Was Difficult to Diagnose

Although methotrexate (MTX) is commonly used to treat rheumatoid arthritis (RA), but it is also known to lead to lymphoproliferative disorders, collectively known as MTX-associated lymphoproliferative disorder (MTX-LPD). We report a case of MTX-LPD that posed a diagnostic challenge as we initially overlooked the patient’s ongoing MTX therapy as a potential cause of the lymphoproliferative disorder.