Bilateral multicentric papillary renal tumors with heteroclonal origin based on tissue‐specific karyotype instability

BACKGROUND: Papillary chromophilic renal tumors were cytogenetically characterized by combined trisomies 7 and 17 along with other numeric chromosome aberrations. They occurred as bilateral multifocal lesions. METHODS: A patient was presented who simultaneously developed bilateral multicentric papillary renal tumors. Tissue specimens from six tumors and tumor-free kidneys were cytogenetically characterized. RESULTS: The tumors showed trisomy of chromosomes 7, 16, and 17 along with various other numeric abnormalities. In normal tissue from both kidneys, a wide variety of clonal and nonclonal numeric and structural chromosome aberrations were found. CONCLUSIONS: The cytogenetic heteroclonality of the tumors strongly favors the assumption that they arose as independent primaries. A tissue-specific karyotype instability may be the basic event of multiple tumorigenesis.