p53 protein expression in mammary and extramammary Paget's disease

p53 is a tumour-suppressor gene, mutations of which are found in malignant skin lesions. We studied the immunohistochemical expression of the (mutated) p53 protein in 17 cases of Paget's disease (12 mammary and 5 extramammary). Four of the mammary specimens (33.3%) expressed p53 within Paget's cells; in one of these an underlying ductal adenocarcinoma was present and this was also p53-positive. All extramammary cases proved p53-negative. These results underline the differences that exist between mammary and extramammary Paget's disease and favour the origin of the former from the underlying adenocarcinoma rather than the surface epithelium.