Cytogenetic and histologic findings in Wilms' tumor

The cytogenetic abnormalities occurring in Wilms' tumors diagnosed and treated at the authors' institution were reviewed. Correlation with tumor histopathology, stage, and outcome were evaluated.

Sixty-seven Wilms' tumors were encountered between 1984 and 1997. Tissue culture was obtained in 63 (94%) cases. Charts were reviewed retrospectively to obtain tumor histopathology, stage, and outcome.

All tumors were examined in accordance with the National Wilms' Tumor Study (NWTS). Sixty-one were unilateral (54 unicentric, 7 multicentric), and 6 were bilateral (2 multicentric). Five Wilms' tumors showed anaplasia, whereas 62 showed favorable histology. Twenty children were stage I, 17 stage II, 20 stage III, 4 stage IV, and 6 stage V. Forty-eight (72%) tumors showed an abnormal karyotype. Chromosomal gain was more common than chromosomal loss, because hyperdiploidy was seen in 30 cases and hypodiploidy in 4. The most common aneuploidies were gains of chromosomes 6, 7, 8, 12, 13, and 18. In general, there was no correlation between specific chromosomal abnormalities with either tumor stage or histologic subtype. The only exceptions were anaplastic changes that were associated with poor prognosis and showed a variety of chromosomal changes including hyperdiploidy, hypodiploidy, and structural rearrangements. The 3 tumors causing mortality exhibited tetraploidy, hypodiploidy, and diploidy with a t(1p:11q) karyotype, respectively. Clonal progression was identified in Wilms' tumors when compared with its accompanying nephrogenic rest. A normal karyotype was seen more commonly in younger patients.

Wilms' tumors display a variety of chromosomal abnormalities. These are particularly seen in anaplastic tumors and are less likely seen in younger patients. Overall, chromosomal gain was more common than loss with trisomies of chromosomes 12, 8, and 6 being the most frequently seen.