[Problems in the morphological assessment of the degree of tumor malignancy]

A scheme is proposed to make a morphological assessment of the tumor malignancy by separately analyzing the degree of their differentiation (as defined by tissue- or organ-specific type formation and structural manifestations of cellular specific functional activity) and that of cataplasia (as evidenced by a set of non specific signs that are largely relative to the proliferative activity of cells). The sense of the terms that denote morphological criteria for the degree of malignancy is discussed. Also, the examples that the degree of differentiation and cataplasia developed at the ultrastructural level is at variance are presented as an explanation for the fact that the clinical course and morphological signs of a tumor cannot coincide.