[Morphological characteristics of angiomyolipoma of the kidneys]

Eight cases of angiomyolipoma of the kidneys were studied. A variant of the tumour in which its vascular component consisted mostly of numerous primitive vascular fissures penetrating the smooth muscle tissue is described. In two cases, perivascular outgrowths of undifferentiated cells of apparently adventitial type were found. In most cases the mature fatty tissue of the tumour is found to have large multinucleate cells assume to be a manifestation of atypical differentiation of precursors of fatty cells. The smooth muscle tissue can be of a various degrees of maturity, and variants of angiomyolipoma may be distinguished in which the muscular component is represented either by highly a differentiated tissue, or by a immature tissue or combination of both.