Methotrexate-associated mantle-cell lymphoma in an elderly man with myasthenia gravis.

BACKGROUND: A 75-year-old man on methotrexate immunosuppression for myasthenia gravis presented with a 2-month history of lymphocytosis and bilateral inguinal adenopathy. There were no constitutional symptoms of fever, night sweats, or weight loss. INVESTIGATIONS: Physical examination, blood tests, flow cytometry, fluorescent in situ hybridization, immunoglobulin gene sequencing, viral load quantification by real-time polymerase chain reaction, excisional lymph-node biopsy, bone-marrow biopsy, tumor morphology and immunohistochemistry, sequential CT and PET scans. DIAGNOSIS: Methotrexate-associated mantle-cell lymphoma. MANAGEMENT: Cessation of methotrexate, anthracycline-based combination chemo-immunotherapy, and maintenance rituximab.