BACKGROUND: Immunosuppression is effective in treating a number of diseases, but adverse effects such as bone marrow suppression, infection, and oncogenesis are of concern. Methotrexate is a key immunosuppressant used to treat rheumatoid arthritis. Although it is effective for many patients, various side effects have been reported, one of the most serious being methotrexate-related lymphoproliferative disorder. While this may occur in various organs, liver involvement is rare. Information on these liver lesions, including clinical characteristics, course, and imaging studies, has not been summarized to date. CASE SUMMARY: We present a case of 70-year-old woman presented with a 2-wk history of fever and abdominal pain. She had had rheumatoid arthritis for 5 years and was being treated with medication including methotrexate. Contrast-enhanced computed tomography revealed multiple low density tumors in the liver and the histological analyses showed significant proliferation of lymphocytes in masses that were positive on immunohistochemical staining for CD3, CD4, CD8, and CD79a but negative for CD20 and CD56. Staining for Epstein-Barr virus-encoded RNA was negative. And based on these findings, the liver tumors were diagnosed as Methotrexate-related lymphoproliferative disorders. A time-dependent disappearance of the liver tumors after stopping methotrexate supported the diagnoses. CONCLUSION: The information obtained from our case and a review of 9 additional cases reported thus far assist physicians who may face the challenge of diagnosing and managing this disorder.