PRECANCEROUS DERMATOSIS AND EPITHELIOMA IN SITU

Abstract

The term "precancerous dermatosis" (precancerosis of Bloch¹) is based on clinical, statistical and histopathologic concepts. The term has been used loosely by many authors² to include many cutaneous diseases in which the incidence of carcinoma is no greater than should be expected when the varying factors of age, senile cutaneous changes, exposure and sensitivity to light, chronic and persistent irritation or trauma and the effects of previous therapy, all of which may predispose to carcinoma, are considered. As a working basis I wish to limit the term "precancerous dermatosis" to true but infrequent Bowen's³ precancerous dermatosis, senile keratosis, keratosis resulting from arsenic, tar or radiation and various forms of leukoplakia of the mucous membrane of the mouth and genitalia, including so-called erythroplasia of Queyrat. I shall show that in 20 per cent or more of cases of all these conditions epithelioma develops, usually of squamous cell