Squamous cell carcinoma in situ, also called Bowen disease, is the earliest form of squamous cell skin cancer. “In situ” means that the cells of these cancers are still only in the epidermis and have not invaded the dermis. Bowen disease appears as reddish patches. Compared with actinic keratoses, Bowen disease patches tend to be larger (sometimes over 1/2 inch across), redder, scalier, and sometimes crusted. Like invasive squamous cell skin cancers, the major risk factor is too much sun exposure. Bowen disease can also occur in the skin of the anal and genital areas. This is often related to.
