[The degree of malignancy and histologic variants of kidney cancer: their importance in diagnosis and prognosis].

Basing on quantitative morphological and histochemical findings, 170 cases of renal carcinoma were divided into 3 (I, II, III) grades of malignancy. This grading system is of a high prognostic significance. Histological variant, i.e. the predominance of clear or granular cells in the tumor specimens, is not prognostically significant. The clear cells differ from the granular ones by high lipid and glycogen content and by low proliferation rate. In tumors of a high malignancy grade the lipid and glycogen levels are low. The authors offer to divide all cases of renal carcinoma not into clear- and granular-cell tumors, but on lipid-rich and lipid-poor ones because the lipid content is in good correlation with the grade of malignancy and therefore prognostically valuable.