p53 protein overexpression in laryngeal squamous cell papillomas

We retrospectively investigated p53 protein immunoreactivity in 103 laryngeal squamous cell papillomas (LP) previously revealed to be human papillomavirus type 6 or 11 positive by in situ hybridization and/or the polymerase chain reaction. 21 LP failed to show any detectable level of p53 protein reactivity. In 45 cases only occasional strongly positive cells were observed in almost the whole thickness of the epithelium. In 26 LP, p53 protein immunoreactivity was found to be almost exclusively restricted to the basal epithelial cells. Finally, in 11 cases, basal cell layer immunoreactivity was accompanied by aggregates of p53-positive cells in the lower two thirds of the epithelium. This staining pattern was found predominantly in LP with atypical hyperplasia. We think that the observed patterns of p53 immunoreactivity in a majority of cases are a result of immunohistochemical detection of the stabilized wild-type p53 protein rather than the mutated p53 protein.