Ultrastructural characteristics of human renal cell carcinoma in relation to the light microscopic grading.

Twenty-two consecutive cases of renal adenocarcinoma were graded histologically according to the nuclear structure of the tumor cells. The ultrastructural characteristics of these tumors were then evaluated and the findings were compared with the results of the nuclear grading. No ultrastructural characteristic was found which would have been specific for either Grade I, II, III or IV carcinomas. There was no ultrastructural features that could have been used as a basis for malignancy grading. The results show that electron microscopy has nothing to add to the nuclear grading system of renal adenocarcinoma and the value of this grading system is to be emphasized.