Neutropenia in Felty's syndrome successfully treated with hydroxychloroquine.

Felty’s syndrome (FS) is a rare disease defined by the presence of 3 conditions: rheumatoid arthritis (RA), neutropenia, and splenomegaly 1. It has been subdivided into two entities, depending on the presence or absence of large granular lymphocyte (LGL) leukaemia. LGL leukaemia is diagnosed by identifying a T cell clone with typical LGL morphology and phenotype in blood or bone marrow smears. However, both entities may be part of the same disease spectrum. Morbidity and mortality rates are high in FS patients, with or without LGL leukaemia, because FS patients are more susceptible to infection. Although little is known about the pathophysiological aspects of FS, neutropenia, a defining feature of FS, may be due to humoral and cell-mediated immune dysregulation. The treatment of FS is not well established due to its rarity and the consequent lack of prospective clinical trials. A number of drugs have been tested yielding various results, but the most efficient treatment seems to be methotrexate (MTX). We report two original cases of severe neutropenia related to FS. Both cases were successfully treated with hydroxychloroquine (HCQ) after methotrexate was withdrawn due to toxicity.