Pseudo Felty's syndrome. A polyclonal disease with a favorable prognosis. Report of two cases with Southern blot analysis of TCR.

The authors report two patients with large granular lymphocyte (LGL) expansion associated with rheumatoid arthritis corresponding to pseudo Felty's syndrome. These cells have natural killer and T cell surface antigen markers. LGL are a heterogeneous population and expansion of these cells is responsible for leukemia, which is generally a monoclonal proliferation. It has been suggested that Epstein-Barr virus (EBV) is a putative agent in this leukemia. No EBV DNA was found with a polymerase chain reaction analysis in the lymphocyte DNA of our two patients. Some cases of pseudo Felty's syndrome have exhibited a monoclonal pattern on Southern blot analysis of the T cell receptor. On the contrary, our two cases showed a polyclonal pattern with TCR beta chain Southern blot analysis. This fact, associated with the mild course seen in both over more than twenty years, suggest that pseudo Felty's syndrome is a disease with a good prognosis.