Background: In sun-exposed nonmelanoma skin cancers, observation of specific p53 gene mutations implicate the role of UV radiation-induced mutations in the pathogenesis of these tumors. Immunohistochemical p53 protein overexpression and p53 gene mutation have been frequently considered related events.
Objective: We investigated the differences in p53 immunostaining in squamous cell carcinomas (SCCs) with varying degrees of differentiation, from both chronically sun-exposed and sun-protected sites of the skin.
Methods: Twenty-six SCCs (15 UV-related and 11 UV-unrelated) and five specimens of Bowen's disease (in situ SCC) from sun-exposed skin were examined by means of BP53-12-1 monoclonal antibody immunohistochemistry.
Results: p53 Immunoreactivity was observed in 66.7% of sun-exposed, 54.5% of non-sun-exposed invasive SCCs (Fisher's exact test, p = 0.689), and 80% of Bowen's disease specimens. In 50% of all samples, p53 positivity was more prominent in the proliferating periphery of the tumor with gradual loss of positivity as the cells differentiated.
Conclusion: The reliability of p53 immunohistochemistry needs further molecular genetic studies.