In 1951, Churg and Strauss first described allergic angiitis and granulomatosis, now commonly referred to as the Churg-Strauss syndrome.49 This syndrome is characterized by necrotizing vasculitis, extravascular granulomata, and tissue infiltration with eosinophils. The annual incidence has been estimated at 2.4 cases per 1,000,000 people,50 and case reports and case series have been published.51-55 Criteria were published by the American College of Rheumatology to increase the sensitivity and specificity of distinguishing Churg-Strauss from other vasculitides.56 The 6 criteria include peripheral eosinophilia of 10% or more in the leukocyte differential, biopsy-proven extravascular eosinophils, asthma, paranasal sinus abnormality, mononeuropathy or polyneuropathy, and nonfixed pulmonary infiltrates.
As in other diseases with eosinophilic infiltration of multiple organs, cardiac involvement can be the major cause of morbidity and mortality. Numerous clinical signs and symptoms of cardiac involvement may be seen.53'57"63 These include presentation with heart failure, pulmonary embolism, myocardial infarction, and signs and symptoms associated with constrictive pericarditis.53'58
Reports in the literature demonstrated the association of tissue and blood eosinophilia with cancer of the lung,64-70 the gastrointestinal tract,71-74 the genitourinary tract,75-91 and the skin.85,92 Eosinophilic myocarditis in this setting has been described.68,93,94
Endomyocardial Fibrosis: Eosinophilic Versus Tropical
Endomyocardial fibrosis is a pathologic diagnosis, describing the replacement of endocardium with thick collagen tissue overlying a looser framework of connective tissue in the involved endomyocardium.95 Although pathologically descriptive, the term "endomyocardial fibrosis" belies the dynamic pathophysiology, especially that of the eosinophil, which contributes to this "end result" and to the debate in distinguishing the 2 entities frequently associated with this pathologic finding: Loffler endomyocardial fibrosis and Davies endomyocardial fibrosis (tropical endomyocardial fibrosis).
As alluded to above, Loffler47 initially described endomyocardial fibrosis in the setting of myocardial eosinophil infiltration within the context of the hypereosinophilic syndrome. The patients in whom this type of endomyocardial fibrosis develops (Loffler endomyocardial fibrosis) are generally male; from geographic regions with temperate climates; and clinically demonstrate fever, rash, weight loss, congestive heart failure, restrictive physiology, and systemic embolization.46,96,97 Eosinophilia and myocardial infiltration with eosinophils are the rule. However, by the time of necropsy or endomyocardial biopsy, the eosinophilic infiltrations may have already stopped, leaving only the remaining endomyocardial fibrosis.
The pathophysiology of endomyocardial disease in HES is associated strikingly with cardiac deposition of eosinophil granule protein initially onto the endocardium and later on the mural thrombi and on myocardial cells.98 Analyses of cardiac tissue from 18 autopsies and biopsies of patients with HES-associated endomyocardial disease revealed dramatic MBP and eosinophil cationic protein deposition, especially during the acute phase of the disease. Surprisingly, MBP deposition in subendocardial fibrous tissue may persist and provide a signal indicative of eosinophil involvement. Because MBP causes platelet activation,99 inhibits the capacity of endothelial cell surface thrombomodulin to generate the natural anticoagulant (activated protein C),99 and activates cardiac mast cells, its deposition may stimulate clot formation directly, with subsequent embolization and encroachment on the ventricular cavity.
Tropical endomyocardial fibrosis (Davies endomyocardial fibrosis) is distributed geographically along the tropical and subtropical regions of Africa, India, and South America.101,102 The sex distribution is approximately equal, and children and young adults are affected most.103,104 Eosinophilia and eosinophilic infiltration of myocardium are not distinct features of this disease.97,101,105
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