2018 Volume 80 Issue 3 Pages 214-218
We report a case of 76-year-old female patient with rheumatoid arthritis, who presented diffuse large B cell lymphoma (DLBCL) developed on the lower leg. Previously, she had been administrated immunosuppressive treatment with methotrexate (MTX) (8 mg/week) and prednisolone (7. 5 mg/day) for 5 years. Physical examination showed sporadic erythema and nodules on the both lower legs, respectively. Topical therapies failed to treat those lesions. After that, the lesions formed a tumor on the left lower leg and formed ulcers on the right lower leg. Histological examination of the left lower leg showed large sized atypical lymphocytes with CD20-positive proliferated in the entire dermis, which demonstrated the diagnosis with DLBCL. In addition, Epstein-Barr virus (EBV) infection in the tumor cells were confirmed by EBV-encoded small RNA and EBV-latent membrane protein 1. On one hand, histological examination of the right lower leg showed oligoclonal proliferating T cells in the superficial dermis. After withdrawal of MTX therapy, the tumor rapidly regressed without chemotherapy. We diagnosed MTX-associated lymphoproliferative disorder (MTX-LPD) appeared as DLBCL due to the histopathological findings and the characteristic clinical course. When we examine a patient under treatment with MTX,we have to keep in mind that there is more risk of MTX-LPD which may induce malignant lymphoma.
