Bowen’s disease (BD) is a very early form of skin cancer confined to the upper layer of the skin. Often termed Squamous Cell Carcinoma in situ, this low-risk malignancy is highly treatable when diagnosed early. Understanding its nature is important for individuals interested in their risk of developing non-melanoma skin cancers. Bowen’s disease is certainly not rare, though its frequency is often misunderstood by the general public.
What is Bowen’s Disease?
Bowen’s disease is medically defined as Squamous Cell Carcinoma in situ (SCC in situ), meaning the abnormal cells are strictly limited to the epidermis, the outermost layer of the skin. The term “in situ” signifies that the cancerous cells are “in their original place.” These abnormal cells have not yet penetrated the basement membrane to invade the deeper, underlying tissue, which would define an invasive cancer.
The disease typically presents as a solitary, slowly enlarging patch or plaque on the skin. This lesion is often reddish-brown, with a clearly defined border and a scaly or crusted surface. Because it grows slowly, sometimes over many years, it can be mistaken for common, benign skin conditions like eczema or psoriasis. Unlike those conditions, however, the patch of Bowen’s disease will not respond to standard moisturizing creams or topical steroids.
How Common is the Condition?
While Bowen’s disease is not as frequently diagnosed as Basal Cell Carcinoma (BCC), it is far from a medical anomaly. It is a common non-melanoma skin cancer seen regularly by dermatologists, particularly in countries with high levels of sun exposure. Incidence rates are highly variable, with studies in fair-skinned populations reporting ranges from approximately 15 to over 140 cases per 100,000 people annually.
The condition occurs most often in older individuals, typically those over the age of 60, due to the cumulative effects of sun damage over a lifetime. It affects fair-skinned individuals disproportionately, aligning with the demographics for most non-melanoma skin cancers. Its frequent occurrence in older adults makes it well-known and routinely managed within dermatological practice. Its prevalence contributes significantly to the overall burden of non-melanoma skin cancers.
Factors That Increase Risk
The primary cause for the development of Bowen’s disease is chronic, long-term exposure to ultraviolet (UV) radiation from sunlight or tanning beds. The cumulative UV damage over decades causes mutations in the skin cells, driving the abnormal proliferation in the epidermis. This accounts for why lesions commonly appear on sun-exposed areas like the head, neck, and lower legs.
Exposure to inorganic arsenic is another established, though less common, factor that can increase risk. This exposure is usually occupational or environmental, such as from contaminated well water or old pesticides. A latency period of approximately ten years or more often precedes the disease’s manifestation, as arsenic is thought to enhance the carcinogenic effects of UV radiation.
Infection with the Human Papillomavirus (HPV), specifically high-risk types like HPV-16, is a significant biological factor. This association is particularly strong for lesions that develop in the genital or perianal regions, sometimes referred to as bowenoid papulosis or Erythroplasia of Queyrat. Additionally, any condition that compromises the body’s natural immune surveillance, such as immunosuppressive medication following organ transplantation, significantly increases the risk of developing Bowen’s disease.
Diagnosis and Treatment Pathways
Diagnosis of Bowen’s disease begins with a thorough clinical examination, as the lesion’s scaly, reddish appearance can mimic several other skin conditions. If BD is suspected, a skin biopsy is performed to confirm the diagnosis and rule out invasive cancer. This procedure involves removing a small sample of the affected skin for microscopic analysis to verify that the abnormal squamous cells are confined to the epidermis.
Due to its superficial nature, treatment success rates for Bowen’s disease are very high, with several effective options available based on the lesion’s size, location, and the patient’s overall health. Surgical excision, which involves cutting out the lesion and a small margin of surrounding healthy tissue, is a common and definitive treatment. This method provides tissue for pathological confirmation of complete removal.
Non-surgical methods are often preferred for larger lesions or those in cosmetically sensitive areas. Cryotherapy involves freezing the lesion with liquid nitrogen, which destroys the abnormal cells. Another ablative technique is curettage and electrodessication, where the lesion is scraped away and the base is cauterized with an electric current.
Topical chemotherapy creams, such as 5-fluorouracil (5-FU) or the immune-response modifier imiquimod, offer a non-invasive treatment option that patients can apply at home. These creams work by selectively killing the rapidly dividing, abnormal cells or by stimulating a localized immune response against them. After treatment, a favorable prognosis is expected, but regular follow-up skin checks are important since individuals who have had Bowen’s disease remain at an increased risk for developing other skin cancers.