Abstract: Gene mutation is known to play an important role in carcinogenesis.There are two types of p53 gene,wild-type and mutant-type.In order to observe the relationship between p53 gene mutation and cutaneous squarnous epithelial ceil tumours,immunohistochemical study was carried out for p53 ex-pression in the epidermis from 29 patients with cutaneous squamous epithelial cell tumouts using a new immunohistochemical technique labelled streptavidin biotin system.The results showed that p53 positive staining was only confined to areas of atypical proliferation of epithelia in 3/6 cases of actinic keratosis. 6/10 cases of Bowen's disease and 8/13 cases of squamous cell carcinoma showed that p53 positive staining was seen throughout the tumour.It is suggested that p53 gene mutation might play an impor-tant role in cutaneous squamous epithlial cell tumour formation.

Key words: p53, Mutation, Cutaneous, Tumour