Histologic and electron microscopy findings in myocardium of treated Fabry disease

SummaryThe well-described histologic and electron microscopic findings in Fabry disease cardiomyopathy are hypertrophic vacuolated cells with electron dense concentric lamellar bodies. We present altered findings in an endomyocardial biopsy from a patient with treated Fabry disease. A 51-year-old male with Fabry disease, treated with recombinant α-galactosidase enzyme replacement therapy for over 18 months, underwent an endomyocardial biopsy for heart failure. The histologic changes showed widespread hypertrophy and vacuolization with rare eosinophilic bodies. Electron microscopy failed to reveal the characteristic globotriaosylceramide concentric lamellar bodies (myelin figures) in the sarcoplasm. Instead, extensive aggregates and single tubular crystalline structures, giant secondary lysosomes as well as abnormal branched chain glycogen were present. This is the first histologic description of long-standing treated Fabry disease in cardiac myocytes.