Endocardial fibroelastosis (microscopic)
This trichrome stained section shows marked thickening of the endocardium with fibrosis. Strands of fibrous tissue
extend into the myocardium. EFE can be primary or secondary to increased wall stress as in aortic valve atresia
or severe stenosis. Primary EFE is now rare. It usually follows intrauterine viral myocarditis, especially mumps.
1 minute clinical correlation