Fig. 7

Histopathological features of the fibromuscular band. a General view of the structure composed by dense, longitudinally oriented fibrous connective tissue (indicated by an asterisk) and myocardium (indicated by an arrowhead) located mostly at the ventral zone (close to the apex). The endocardium presents areas of nodular hyperplasia. b Detail of the area demarcated by the small rectangle in image 7A, presenting the plexiform pattern of the myocardium (indicated by the arrowheads) and the adjacent densely packed fibrous connective tissue (indicated by an asterisk). c Detail of the area demarcated by the large rectangle in image 7A. The fibromuscular band shows areas of hyperplasia, marked by sparsely cellular nodules of loose myxoid connective tissue covered by hyperplastic endocardium. d A myxoid nodule sharply demarcated from the surrounding myocardium (indicated by the arrowhead), composed of abundant, basophilic extracellular matrix and loosely arranged fibroblasts. H&E stain, ob. X 4 for image A, ×20 for images B and D, and ob.× 10 for image C