NONPAPILLARY AND PAPILLARY RENAL-CELL CARCINOMA - A CYTOGENETIC AND PHENOTYPIC STUDY

Cytogenetic and molecular genetic studies allow the common renal cell neoplasms to be separated into two main types: (1) Nonpapillary renal cell carcinomas (RCC) which have a loss of 3p13-pter sequences and (2) Papillary renal cell tumors having tri- or tetrasomies of chromosome 7 and trisomy 17. To investigate renal proximal (PT) and distal (DT) t ubular epithelial phenotype expression in these genetically distinct n eoplasms, a panel of antibodies and lectins selectively reactive with normal adult PT and DT was applied to 10 nonpapillary and seven papill ary RCC. All tumors except one papillary RCC demonstrated characterist ic karyotypes. Phenotype expression varied depending upon changes in t he histopathologic patterns within a tumor. Among tumors composed of o nly one cell type, columnar, eosinophilic cells showed only PT stainin g and small, basophilic cells showed only DT staining. One tumor revea led a transition from small, basophilic cells to columnar, eosinophili c cells. The basophilic cells stained for DT markers and the eosinophi lic cells for PT markers. One tumor consisted of nests of clear cells between indistinct papillary structures. The clear cells stained for b oth PT and DT markers. All 10 nonpapillary RCC demonstrated PT stainin g; nine exhibited DT markers. Staining was most intense in areas of tu mor showing higher nuclear grades, tubuloglandular differentiation or in granular, eosinophilic cells and was absent or weak in solid groups of low nuclear grade clear cells. Papillary and nonpapillary RCC demo nstrated lectin-binding or antigens associated with both PT and DT ind icating a capacity for multipotential metanephric differentiation in e ach type of neoplasm. The similarity of histopathology and of PT and D T staining in some cases points out a need for cytogenetic studies to discriminate between the two types of tumors when they present ambiguo us histologic features.