Objective:To study the clinical and pathological features

malignancy and prognosis of keratoacanthoma(KA).Methods: Eighteen patients with KA were collected

and their clinical features were analyzed with pathological aspects observed by immunohistochemical SP techniques.Results:The typical lesion of KA is a hemispheric

dome-shaped

skin-colored nodule in which there is a smooth crater filled with a central keratin plug.Histological examination showed a crater filled with eosinophilic keratin.A"lip"formed by invagination of epidermis surrounds the keratin-filled crater.Wide excision of the lesions is the first choice for the treatment of KA. The expression levels of p53 was higher than controls(P<0.05).No statistical significance were found on the expression of bcl-2 and P-gp.Conclusions:KA is a skin malignant tumor with it’s typical clinical and pathological features. The diagnosis

malignancy and prognosis of KA can be confirmed by immunohistochemical staining.