Long-term remission of T-cell large granular lymphocyte leukemia associated with rheumatoid arthritis after rituximab therapy.

T-cell large granular lymphocyte leukemia (LGLL) is a rare clonal disease often associated with rheumatoid arthritis (RA) and manifests chiefly as neutropenia and recurrent infections. Immunosuppressive agents are the mainstay of treatment, but long-term remissions are rare. We report 2 cases of LGLL in patients with RA successfully treated with rituximab, a monoclonal antibody specific of B cells and approved for treating RA. The first patient experienced a complete LGLL remission that was sustained during the 8-year follow-up after the first rituximab infusion. In the second patient, rituximab therapy was followed by immediate neutropenia recovery and then by marked shrinkage of the LGLL clone 1 year later. The paradoxical efficacy of this specific anti-B-cell drug on a monoclonal T-cell disease suggests that some cases of LGLL may be reactive manifestations of chronic autoantigen stimulation rather than true malignancies.