Observations by chromosome banding, FISH and immunohistochemistry in an adenoid cystic carcinoma with del(17)(p13) as the sole deviation

We report on an adenoid cystic carcinoma (ACC) with a clonal deletion of 17p as the only karyotypic abnormality. Using different chromosome 17-derived probes we showed by FISH that the deletion encompassed the p53 tumour suppressor gene. Immunohistochemical analysis revealed overexpression of p53 protein in a subpopulation of cells, suggesting a mutation in the remaining p53 allele in these cells. Our findings provide novel information about possible progressional pathways in ACC, and demonstrate the value of combining conventional cytogenetic analysis with molecular cytogenetic and immunohistochemical methods. This approach is particularly useful in cases with minor cytogenetic abnormalities at the border of visibility.