Epstein‐Barr virus‐related diffuse large B‐cell lymphoma type methotrexate‐associated lymphoproliferative disorders presenting in the adrenal gland

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.