Fig. 1.

Gross and microscopic features of hypertrophic cardiomyopathy: HCM is characterized by focal lesions of replacement fibrosis within regions of gross hypertrophy as well as subendocardial fibrosis. Extensive small arterial remodeling is observed in these regions but not exclusively. The inset portrays mid-myocardial features associated with affected myocardial tissue: myofiber disarray, perivascular fibrosis (increased collagen deposition is indicated by blue as would be with Masson Trichrome staining), microvascular rarefaction, ischemic cardiac remodeling, interstitial fibrosis. Bottom right portrays a cross-section through an intra-mural artery undergoing typical changes observed during vascular injury (fibromuscular dysplasia), which include myofibroblast trans-differentiation and activation, medial hypertrophy, smooth muscle cell intimal infiltration and elaboration of extracellular matrix, and breakdown of the internal elastic membrane