Methotrexate-associated EBV-positive vasculitis in the skin: a report of two cases simulating rheumatoid vasculitis.

Rheumatoid vasculitis (RV) is one of the most serious extra-articular complications of rheumatoid arthritis (RA), generally treated with a high dose of immunosuppressive drugs. Recently, we encountered two cases of ulcerative vasculitis in methotrexate (MTX)-prescribed RA patients, which simulated RV; however, Epstein-Barr virus (EBV)-encoded RNA in situ hybridization on their skin biopsies revealed many EBV-positive lymphocytes (over 50 cells/high-power field) within the vessel walls and perivascular stroma, which led us to the diagnosis of EBV-related vasculitis instead of RV. Subsequently, both ulcers regressed after the discontinuation of MTX and no recurrence was noted during the follow-up period. To prevent unnecessary treatment, EBV-positive vasculitis should be added in the differential diagnosis of lymphocytic vasculitis observed in MTX-administered RA patients.