Heteromorphic grade of renal cell cancer.

The present study demonstrates by means of histopathologic analysis that most of the renal adenocarcinomas are microscopically heterogeneous--named by authors as heteromorphic. This heteromorphism means the mixture of different cell types, histological patterns and fields of tumor with different nuclear atypia. 300 surgical specimens of renal cell cancer (RCC) were reclassified retrospectively. The histologic classification was as follows: 1. Nuclear atypia (nuclear grading according to Skinner); 2. Histological structure (compact, tubular, papillary, cystic); 3. Tumor cell types (clear, chromophobe, chromophilic basophilic, chromophilic eosinophilic). Homogeneous tumors consist of the three categories of this basic classifications. Heteromorphic tumors have combinations the three categories: different cell types (clear and granular) and/or histological elements (tubulo-papillary) and/or nuclear structure. Heteromorphism of RCC can be graded as: G-I: homogeneous structure (three patterns, one-one pattern of the three categories; G-II: 3 + 1 patterns.... G-III: 3 + 2 patterns.... G-IV: 3 + 3 or more patterns of the classification given above. This grading system is recommended for the heteromorphism of renal adenocarcinomas.