Chromosome constitution of nephroblastomas

Chromosome preparations were made by a direct method, without preliminary tissue culture, from 7 untreated primary nephroblastomas. Analysis showed that 4 of the tumors had an abnormal chromosome set. One of these was pseudodiploid and in the other 3 the distribution of chromosome numbers was 45 to 49, 44 to 48 and 44 to 58. The remaining 3 tumors had a modal number of 46 and an apparently normal karyotype. In comparison with adult tumors relatively small chromosome changes were observed. The changes were more similar to the condition in acute leukemia, where slight chromosome abnormalities or even normal chromosomes are found.