Two chromosomally different cell populations in a human neoplasm

A biopsy specimen of a liver metastasis of a rapidly progressing renal adenocarcinoma was chromosomally investigated. Of the metaphases studied 40% represented the karyotype of the tumor, the chromosome number being in the triploid region. A characteristic set of chromosome markers was constantly present in these metaphases. The main part of the metaphases studied, however, had a normal diploid karyotype. These cells assumedly represent normal host cells stimulated to mitotic activity by the presence of the neoplasm. The host cells seem to be intimately associated with the neoplastic tissue. The dividing host cells most probably represent immunologically activated cells.