The spectrum of large granular lymphocyte leukemia and Felty's syndrome

Purpose of review Patients with chronic large granular lymphocyte (LGL) leukemia often have rheumatoid arthritis (RA), neutropenia and splenomegaly, thereby resembling the manifestations observed in patients with Felty's syndrome, which is a rare complication of RA characterized by neutropenia and splenomegaly. Both entities have similar clinical and laboratory presentation, as well as a common genetic determinant, HLA-DR4, indicating they may be part of the same disease spectrum. This review paper seeks to discuss the underlying pathogenesis and therapeutic algorithm of RA, neutropenia and splenomegaly in the spectrum of LGL leukemia and Felty's syndrome. Recent findings We hypothesize that there may be a common pathogenic mechanism between LGL leukemia and typical Felty's syndrome. Phenotypic and functional data have strongly suggested that CD3(+) LGL leukemia is antigen-activated. Aberrations in the T-cell repertoire with the emergence of oligoclonal/clonal lymphoid populations have been found to play a pivotal role in pathogenesis of RA. The biologic properties of the pivotal T cell involved in RA pathogenesis are remarkably similar to those in leukemic LGL. Summary RA-associated T-cell LGL leukemia and articular manifestations of typical Felty's syndrome are not distinguishable. A common pathogenetic link between LGL leukemia and RA is proposed.