RESUMO
Introduction: Methotrexate-associated lymphoproliferative disorders appear during treatment with methotrexate as an immunosuppressive drug. However, the mechanism and frequency are still unknown, and the treatment is undefined. Case presentation: A 76-year-old woman was admitted to the hospital with back pain, and magnetic resonance imaging showed a tumor in the right adrenal region. She had received methotrexate for rheumatoid arthritis. Enhanced computed tomography showed a tumor of 90 mm in diameter on the dorsal side of the liver abutting to the inferior vena cava. The preoperative diagnosis was a hepatic invasion of right adrenocortical carcinoma and right adrenalectomy was performed. The histopathological diagnosis was diffuse large B-cell lymphoma. The final diagnosis was methotrexate-associated lymphoproliferative disorders. Conclusion: It is important to consider methotrexate-associated lymphoproliferative disorders before surgery when neoplastic lesions are found in patients taking methotrexate.