EBV-associated diffuse large B-cell lymphoma in a psoriatic treated with methotrexate.

Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a lymphoid proliferation or lymphoma in a patient immunosuppressed with MTX, which is usually administered for treating autoimmune diseases. The majority of MTX-LPD cases develop in patients with rheumatoid arthritis and occasionally with psoriasis who had been treated with MTX. Here, we report on a 50-year-old Taiwanese male with severe psoriasis, who received high doses of MTX. The patient developed EBV-positive MTX-LPD at nodal and extranodal sites. The diffuse and polymorphic lymphoid infiltrate consisted predominantly of immunoblasts and plasmablasts expressing B-cell markers, CD138, Epstein-Barr virus (EBV)-LMP1, and EBNA2, and these were monotypic for kappa light chain. The tumor cells were also positive for EBV by in situ hybridization. These findings indicated a type III latency infection of EBV. The patient died of progressive disease after 19 months. A review of the previously reported cases shows that MTX-LPD, in association with psoriasis, occurs in middle-aged males. The tumors are diffuse large B-cell lymphomas with immunoblastic morphology, and frequently show plasmacytic differentiation.