Cytogenetic findings in Wilms' tumour: a single institute study.

Aims: Cytogenetic abnormalities of Wilms' tumour (WT) treated in a single institution in Western Australia were reviewed. Correlation with histologic subtypes, stage, presence of nephrogenic rests and age of the patient at diagnosis were also evaluated.

Methods: 53 WT specimens were encountered between 1995 and 2009. Tissue culture was obtained in 49 (92%) specimens. Reports documenting histopathological features of the tumour, stage and outcome were also retrieved.

Results: A total of 53 tumour specimens from 42 patients/cases were examined and staged in accordance with the National Wilms' Tumor Study (NWTS). Thirty-eight cases were unilateral (34 unifocal, 4 multifocal) and four were bilateral (2 multifocal). Fifty tumours showed favourable histology WT. One tumour was a cystic partially differentiated nephroblastoma (CPDN). Two tumours showed diffuse anaplasia. Eighteen specimens had nephrogenic rests, seven with perilobar rests, 10 with intralobar rests and one with both types of nephrogenic rests. Twelve WTs were assigned as stage 1, 22 as stage 2, 16 as stage 3, and two each for stages 4 and 5. For chromosomal analysis, 92% of the specimens yielded results, of which 70% showed abnormal karyotype and 22% displayed normal karyotypic findings. Hyperdiploidy was more common than hypodiploidy. The most common chromosomal gain involved chromosome 12. Low stage tumours tended to have abnormal karyotypes with hyperdiploidy and hypodiploidy being more common. There was no statistical correlation between abnormal karyotype and stage or abnormal karyotype and age group or abnormal karyotype and non-blastemal WT. Eleven (58%) tumours harbouring nephrogenic rests displayed an abnormal karyotype. 16q loss or der(16)t(1;16) were more common in younger patients but no association was made between this chromosomal abnormality and stage. Monosomy 22 and gain of 1q were more common in older patients. Furthermore, monosomy 22 tended to occur in tumours of earlier stage. No correlation between 11p deletions and age or stage was seen.

Conclusions: WTs are karyotypically heterogeneous tumours. Conventional cytogenetic analysis of WTs still remains a useful technique to assist in the understanding of these tumours.