Hypereosinophilic syndrome with isolated Loeffler's endocarditis: complete resolution with corticosteroids

Hypereosinophilic syndrome (HES) is classically defined as prolonged, unexplained peripheral eosinophilia in a patient presenting with evidence of end-organ damage. The heart is involved in two forms; endomyocardial fibrosis (Davies disease) and eosinophilic endocarditis (Loffler's endocarditis). It was first reported in 1968 by Hard and Anderson. Chusid and co-workers formulated a definition with strict criteria for the diagnosis of HES as 1) peripheral blood eosinophilia more than 1500 cells/cu mm for at least six months duration 2)signs, symptoms of end-organ (heart, lungs, gastrointestinal tract, skin, bone-marrow, brain) involvement with eosinophil tissue infiltration/injury 3) exclusion of known secondary causes of eosinophilia. We report a case of hypereosinophilic syndrome with Loffler's endocarditis, in the absence of endomyocardial fibrosis. The patient presented with a eosinophilic vegetation over the posterior leaflet of the mitral valve. There was complete resolution of the vegetation after two months of corticosteroid therapy.