Pulmonary Intravascular Large B-cell Lymphoma in a Patient Administered Methotrexate for Rheumatoid Arthritis.

A 70-year-old woman with rheumatoid arthritis undergoing methotrexate (MTX) treatment presented with dyspnea and a subfever. Computed tomography (CT) revealed a diffuse minimal ground-glass appearance in both lungs and splenomegaly. The gallium scintigram showed a diffuse, mild uptake in both lungs and the spleen. The lung biopsy specimen revealed the presence of CD20-positive atypical lymphocytes in the small pulmonary vessels. The patient was diagnosed with pulmonary intravascular diffuse large B-cell lymphoma (IVLBCL) and exhibited spontaneous regression after MTX was discontinued. This report describes a rare case of MTX-associated lymphoproliferative disorder expressing pulmonary IVLBCL.