Cutaneous squamous cell carcinoma in situ (SCCis), also known as Bowen disease, is defined histopathologically by malignant keratinocytes that involve the full thickness of the epidermis. This common malignancy is primarily seen in older adults and most frequently occurs on sun-exposed skin. The development of SCCis has also been associated with immunosuppression, chronic lymphocytic leukemia, radiation exposure, arsenic ingestion, and human papillomavirus (HPV). There is no sex predilection. It is frequently seen accompanying other stigmata of chronic sun damage, such as actinic keratoses, solar lentigines, and other keratinocytic carcinomas. If left untreated, SCCis can evolve into invasive SCC.