Ultrastructural typing of renal cell carcinoma （RCC）

30 cases ot RCC, including 16 clear, 1 spindle and 6 mixed （clear and granular）, were carefully compared in their ultrastructural characteristics. The clear, granular and spindle cell type of RCC were not different in nature but rather in the quantity of lipid, glycogen and mitochondria present. So, ultrastructually, RCC may be classified into 3 types: that rich in lipid and/or glycogen （clear）, that rich in mitochondria （granular） and that poor in lipid and mitochondria （spindle）. It was also found that the degree in ultrastructural differention can be of value in prognosing the RCC.