Expression of p53 and p16 in actinic keratosis, bowenoid actinic keratosis and Bowen's disease.

Introduction  Bowen's disease (BD) and bowenoid actinic keratosis (bAK) have traditionally been differentiated according to the presence or absence of dysplasia in the follicular epithelium. p16 has been suggested to be a useful tool to make the differential diagnosis between BD and AK and as a marker of bad prognosis. Materials  Five biopsies of BD, five of AK and five of bAK where stained for p53 and p16. Results  All lesions showed positive immunostaining of p53, affecting to the lower two thirdss of the epidermis in BD and bAK, and only the basal layer in non-bAK. All the BD and bAK cases were positive for p16, showing a similar immunostaining pattern, whereas no staining was observed in non-bAK. Discussion and conclusion  These findings suggest a common pathogenic mechanism for BD and bAK. bAK might have worse prognosis than AK. p16 might not be useful as a tool for differential diagnosis between AK and BD because bAK and BD show an extremely similar immunohistochemical pattern.