[Primary thrombocythemia in a female carrier of IgA deficiency].

We describe a case of essential thrombocythemia observed in a 67-year-old woman with severe IgA-deficiency. The the best of our knowledge, this is the first report concerning the onset of a chronic myeloproliferative disease (CMPD) in a patient affected with primary immunodeficiency, in particular IgA-defect. The association may be merely coincidental; otherwise hemopoietic growth factors acting on myeloid progenitor cells could play a role in this relationship. It has recently been shown that serum levels of many cytokines are elevated in patients with CMPD and probably contribute to enhance proliferation of the malignant clones; on the other hand interleukin-6 seems to account for reactive thrombocytosis, and significant amounts of circulating interleukin-4 and interleukin-6 have been detected in IgA-deficient patients. Overproduction of the two cytokines may depend on recurrent infections, but it could also represent a primary abnormality, with a putative role in the pathogenesis of the immune defect. These findings suggest that high levels of growth factors could induce myeloid hyperproliferation and so expose stem cells to genetic mutations responsible for malignant transformation.