The expression of p63 and p53 in keratoacanthoma and intraepidermal and invasive neoplasms of the skin.

p53 is a well-known tumor suppressor gene, and its mutation is a common event in intraepidermal and invasive neoplasms of the skin. p63 is a homologue of the tumor suppressor gene p53, which is expressed in human basal squamous epithelium, and despite its homology to p53, it is considered to act as an oncogene. We evaluated p63 and p53 expression in usual skin cancers, including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), keratoacanthoma (KA), and intraepidermal neoplasms, including Bowen's disease (BD), actinic keratosis (AK), malignant melanoma in situ (MM in situ), and Paget's disease (PD) to clarify the putative role of p63 and p53 in the development and differential diagnosis of these lesions. Seventeen SCC, 23 BCC, 16 KA, 26 AK, 22 BD, 7 MM in situ, and 6 PD were included in this study. We determined decreasing p63 staining in BD, AK, BCC, SCC, and KA, respectively. None of the MM in situ and PD was positive for p63. The mean p53 staining was highest in BD, followed by AK, SCC, PD, KA, BCC, and normal skin. There was no correlation between the groups in terms of p63 and p53 staining. Based on our findings, analysis of p63 expression may be helpful in the differential diagnosis of BD and AK versus MM in situ and PD, particularly in small biopsies.