Endothelial alterations of skeletal muscle capillaries in childhood myopathies.

Intramuscular blood capillaries in thirteen biopsied specimens obtained from eleven patients with various childhood myopathies were investigated ultrastructurally. The patients were classified into 4 different groups according to the percent distribution of various stages of endothelial alteration; normal endothelial type (E0 Type), slightly abnormal type (E1 Type), moderately abnormal type (E2 Type) and markedly abnormal type (E3 Type). Endothelial types in Duchenne dystrophy progressed from E0 to E1 and further to E2 Type, which kept pace with muscle degeneration. The endothelial types in Werdnig-Hoffmann disease and central core disease were E0 and those in multicore disease and Fukuyama type congenital muscular dystrophy were E1. Two cases of mitochondrial myopathy showed E3 Type, which was characterized by markedly swollen endothelial cells and narrowed lumens. The endothelium in these two cases showed more marked changes than in other childhood myopathies.