Background: The idiopathic hypereosinophilic syndrome (IHS) is a rare entity of unknown etiology. Hematological and cardiac involvement is predominant. A series of 12 patients with this syndrome, initiated in 1982, is described.
Methods: Cardiological study by repeated echocardiograms and hematological study in peripheral blood and bone marrow upon initiation of the disease were performed.
Results: Median follow up was of 48 +/- 31 months. Males predominated (75%) with mean age being 55 +/- 15 years. The principal organs or systems involved were the heart (50%) and the nervous system (41%). Of the 6 cases with cardiac involvement only 2 had clinical manifestations. The remaining 4 patients were diagnosed from echocardiographic changes with the principal alterations observed being: atypical occupation of the ventricles, endocardial thickening and mitral and tricuspid subvalvular cumulus. Echocardiographic follow-up only showed changes in one case. Hematological involvement was characterized by moderate leukocytosis with hypereosinophilia formed by mature eosinophils, conservation of other hematopoietic series, absence of blasts in peripheral blood, finding suggestive of diseosinophilopoiesis and appearance of myelofibrosis and cytogenetic alterations. Survival at four years was 58%.
Conclusions: In the series studied cardiac involvement is frequent, being principally diagnosed in a subclinical phase and with a very slow echocardiographic evolution. At a hematological level changes typical in myelodysplastic syndromes and myeloid leukemia were observed.