Bowen Disease is a slow-growing, early form of skin cancer that develops in the outermost layer of the skin. While classified as a carcinoma, it is non-invasive, meaning the abnormal cells have not spread deeper into the skin layers. When identified early, it is highly treatable with an excellent prognosis.
Defining Bowen Disease
Bowen Disease (BD) is medically classified as Squamous Cell Carcinoma in Situ (SCC in situ). The term “in situ” confirms that the cancerous cells are entirely confined to the epidermis, the top layer of skin. These cells have not yet penetrated the basement membrane to invade the underlying dermis, distinguishing BD from invasive Squamous Cell Carcinoma (SCC).
Because the disease is non-invasive and localized, it typically progresses very slowly over months or years. If left untreated, there is a small potential—estimated at three to five percent—for it to evolve into invasive SCC, which can then spread to other parts of the body. This low rate of progression means that BD requires treatment to prevent the possibility of a more serious cancer developing.
Recognizing the Signs of Bowen Disease
The condition generally presents as a persistent, slow-enlarging patch or plaque on the skin that does not heal. This patch is most commonly reddish-brown or pinkish-red, often featuring a scaly or crusty surface. The borders of the lesion are typically well-defined or irregular, distinguishing it visually from some other skin conditions.
It is often mistaken for common dermatological issues like eczema, psoriasis, or a fungal infection because of its scaly and sometimes itchy appearance. BD lesions do not usually respond to standard topical treatments, which can indicate that a different diagnosis is necessary. Over time, the patch may become slightly raised, thicker, or develop a crack that occasionally bleeds.
Bowen Disease can appear anywhere on the body, including the mucous membranes, but it frequently occurs on sun-exposed areas like the face, neck, and arms. In women, the lower legs are a particularly common site for lesions to develop. When BD affects the genital or anal area, it is sometimes associated with Human Papillomavirus (HPV) infection and may present as velvety red patches.
Primary Causes and Risk Factors
The development of Bowen Disease is strongly linked to chronic exposure to ultraviolet (UV) radiation from sources like sunlight and tanning beds. UV radiation damages the DNA within skin cells over time, leading to the abnormal changes seen in the epidermis. This explains why the condition is most often found on areas of the body with significant lifetime sun exposure.
While UV exposure is the most frequent cause, other factors increase the risk of developing the disease. Infection with certain strains of the Human Papillomavirus (HPV), particularly type 16, is a known cause, especially for lesions found in the genital or perianal regions. Exposure to arsenic, often through contaminated drinking water, is also a recognized, though less common, risk factor.
The disease is diagnosed most frequently in older adults, with the highest incidence occurring in people over 60. Individuals with fair skin are more susceptible due to their vulnerability to sun damage. People who have a compromised immune system, such as organ transplant recipients taking immunosuppressive medications, also have a higher risk of developing BD.
Treatment and Long-Term Monitoring
Before treatment begins, a definitive diagnosis is established through a skin biopsy, where a small sample of the affected tissue is removed and examined under a microscope. The goal of treatment is to completely remove or destroy the cancerous cells confined to the epidermis. The chosen method depends on the lesion’s size, location, and the patient’s overall health.
Surgical excision is a common and preferred option for smaller lesions, involving cutting out the entire affected area along with a small margin of surrounding healthy skin. For lesions in less sensitive areas, curettage and electrodesiccation may be used, which involves scraping away the abnormal tissue and then using an electric current to destroy any remaining cancer cells. Cryotherapy, or freezing the lesion with liquid nitrogen, is another established method often used for small, single lesions.
Non-surgical approaches are often employed, particularly for larger or more numerous lesions, or those located in cosmetically sensitive areas. Topical chemotherapy creams, such as 5-fluorouracil (5-FU) or imiquimod, are applied directly to the skin over a period of weeks to destroy the abnormal cells. Photodynamic therapy (PDT) is a two-step process involving applying a light-sensitizing drug to the lesion, which is then activated by a specific light source to destroy the cancerous cells.
Following successful treatment, long-term monitoring is necessary because having had Bowen Disease indicates an increased risk for developing other forms of skin cancer, including invasive SCC or Basal Cell Carcinoma. Regular, full-body skin checks with a dermatologist are recommended to ensure any new or recurring lesions are detected early. This ongoing vigilance is a component of post-treatment care.