[Renal cell carcinoma--a classification based on cytomorphological criteria].

535 human renal cell carcinomas were classified using a classification system based on defined tumor cell types. The following tumor cell types were distinguished: clear cells (with variants: clear cell-eosinophilic, plasma-rich), chromophobe cells (with variants: eosinophilic, relatively light), chromophilic cells (basophilic, eosinophilic), spindleshaped/-pleomorphic cells. A group "still unclassified" is added. This classification largely rejects the term "granular" (which as a rule was combined with "eosinophilic"), because in our view this term referred to a heterogenic group of variants of different cell types. A cytological grading--based on nuclear morphology--is conducted using 3 grades (GI - III). Preliminary results from follow up studies (survival rates, metastases) suggest that this classification may also have clinical importance for tumor prognosis.