P53 PROTEIN OVEREXPRESSION IN LARYNGEAL SQUAMOUS-CELL PAPILLOMAS

We retrospectively investigated p53 protein immunoreactivity in 103 la ryngeal squamous cell papillomas (LP) previously revealed to be human papillomavirus type 6 or 11 positive by in situ hybridization and/or t he polymerase chain reaction. 21 LP failed to show any detectable leve l of p53 protein reactivity. In 45 cases only occasional strongly posi tive cells were observed in almost the whole thickness of the epitheli um. In 26 LP, p53 protein immunoreactivity was found to be almost excl usively restricted to the basal epithelial cells. Finally, in 11 cases , basal cell layer immunoreactivity was accompanied by aggregates of p 53-positive cells in the lower two thirds of the epithelium. This stai ning pattern was found predominately in LP with atypical hyperplasia. We think that the observed patterns of p53 immunoreactivity in a major ity of cases are a result of immunohistochemical detection of the stab ilized wild-type p53 protein rather than the mutated p53 protein.