Reversible methotrexate-associated lymphoproliferative disorder (MTX-LPD) associated with Epstein–Barr virus in a patient with rheumatoid arthritis

Methotrexate (MTX) has been used as standard therapy for patients with rheumatoid arthritis (RA). MTX-related lymphoproliferative disorder (MTX-LPD) is a heterogeneous group of lymphoid proliferations or lymphomas that can develop in patients treated using MTX. We report a case of MTX-LPD presenting as a tongue ulcer in a patient with RA.An 82-year-old man had complained of ulcer and pain on his tongue and was referred to our hospital. He had RA for 10 years, and had been medicated with MTX (5 mg/week) for the last 8 years. He had a necrotic and deep ulcer at the right tongue. CT examination identified a large tumorous lesion at the right side of the tongue and multiple neck node swellings. FDG-PET confirmed the lesion, showing accumulation SUV max of 18.2. Microscopic examination demonstrated a lymphocytic infiltrate with increasingly atypical histopathological features. Immunohistochemistry showed that the large atypical cells were positive for CD20 and Epstein–Barr virus (EBV). Based on these findings a final diagnosis of MTX-LPD associated with EBV was made. He discontinued use of MTX and the tongue pain gradually decreased and the ulcer disappeared in consequence. There had been no sign of recurrence for 15 months since the withdrawal of MTX.