to the editor: A 70-year-old man with chronic renal disease, splenomegaly, and eosinophilia presented with transient weakness in the left arm, visual disturbances, disequilibrium, and anomia. Magnetic resonance imaging of the brain showed findings consistent with numerous, small em-bolic strokes. Four echocardiograms, including a transesophageal echocardiogram, did not reveal abnormalities. Therapeutic trials of glucocorti-coids and imatinib were unsuccessful at reducing the numbers of peripheral-blood eosinophils. To investigate the possibility that the emboli were the sequelae of eosinophilic endomyocardial disease, the patient underwent a biopsy of his right ventricle and intraventricular septum. Staining of the myocardium with hematoxylin and eosin did not show clinically significant abnormalities. Notably, only rare eosinophils were detected in the interstitium (Fig. 1A and 1B). However, immuno-histologic examination with fluorescein-conjugat-ed antibodies to eosinophil granule major basic protein 1 (MBP1) revealed striking extracellular deposits of eosinophil granule MBP1 (Fig. 1C and 1D). The eosinophil granule MBP1 was most prominent at apparent luminal surfaces, especially over an area of endocardium that stained most intensely.
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