Methotrexate-associated lymphoproliferative disorders are rare immunodeficiency-associated lymphoproliferative diseases characterized by lymphoid proliferation or lymphomas (large B-cell lymphoma, T-cell lymphoma, Hodgkin lymphoma, reactive lymphadenitis and a polymorphic post-transplant lymphoproliferative disorder) that develop in patients with different autoimmune diseases treated with methotrexate. Swelling is the predominant manifestation of the disease and regression after methotrexate withdrawal is observed in a significant proportion of patients.