Bowen Disease

Bowen disease is an early stage of squamous cell carcinoma, a form of skin cancer that involves a group of cells called squamous keratinocytes. Squamous cell carcinoma is the second most common type of skin cancer, and it can be divided into three stages: actinic keratosis, Bowen disease, and invasive squamous cell carcinoma. Actinic keratosis is a precancerous lesion where keratinocytes are damaged by radiation and begin to overproduce keratin. Over time, these damaged keratinocytes can become malignant and develop into squamous cell carcinoma. On the other hand, Bowen disease is considered to be a form of squamous cell carcinoma in situ because cancer cells can be found in the epidermis but have not yet invaded the basement membrane. As squamous cell carcinoma becomes more invasive, it can invade the basement membrane and extend into the dermis and hypodermis; from there, it can metastasize to other parts of the body. 

There are a number of risk factors that can cause Bowen disease: the most important one being exposure to ultraviolet (UV) radiation from the sun or tanning booths. In general, fair skinned individuals are considered to be at a higher risk of developing skin cancer, and the risk increases with sun exposure over time. Other risk factors for Bowen disease include a weakened immune system (e.g., secondary to solid organ transplantation, HIV infection, or long-term glucocorticoid use), arsenic exposure, and human papillomavirus (HPV) infection. HPV infection is a common sexually transmitted infection (STI) that is generally asymptomatic but can sometimes lead to the development of premalignant and malignant lesions (including cervical cancer) in the anogenital area. Although the relationship is unclear, it has also been associated with cutaneous squamous cell carcinoma. 

Bowen disease usually presents as small, well-circumscribed, red or brown patches on the skin with scaly plaques on top. Most cases occur on sun-exposed skin regions, particularly the face, ears, neck, and hands; however, it is also possible for squamous cell carcinoma to develop on sun-protected areas, such as the legs and genitals. Bowen disease tends to grow slowly over months and years. Signs like rapid growth of the lesion, ulceration, bleeding, or pain should arouse suspicion of progression to invasive squamous cell carcinoma. 

Diagnosis of Bowen disease starts with skin examination assessing the characteristics of the lesion as well as a detailed history of the current skin lesion, time of onset, duration, location, and evolution. Dermoscopy typically follows, which is a noninvasive technique that uses a magnifying lens to visualize skin structures that would otherwise not be visible to the naked eye. If Bowen disease or other form of skin cancer is suspected, a tissue biopsy including the subcutaneous tissue may be performed to confirm the diagnosis. On skin biopsy, Bowen disease reveals atypical keratinocytes that involve the full thickness of the epidermis without infiltration into the dermis. 

In the anogenital area, Bowen disease should be distinguished from bowenoid papulosis, a premalignant lesion that presents as solitary or multiple small pink, brown, or violaceous papules that can resemble genital warts. Bowenoid papulosis is considered a sexually transmitted infection caused by high-risk human papillomavirus, particularly HPV 16.

There are several treatment options for Bowen disease, both surgical and non-surgical. Surgery is the preferred treatment for Bowen disease and squamous cell carcinoma. Options include standard surgical excision and Mohs surgery: a very precise technique used on high-risk sites, such as the face or genitalia. 

Non-surgical treatments may be performed in selected cases and include curettage and electrodesiccation, cryotherapy, photodynamic therapy, and topical medications. Curettage and electrodesiccation is one of the simplest, safest, and most effective treatments for Bowen disease; however, it can only be performed on small, solitary lesions that have a low risk of progression to invasive disease. It typically involves scraping out the lesion with a curette and then applying light cautery to stop the bleeding. Another alternative is cryotherapy, where the tumor is frozen off with liquid nitrogen. This technique is typically used in individuals with multiple lesions. Side effects of the procedure can include local discomfort and pain, ulceration, and long healing times. Next, photodynamic therapy is a treatment that uses photosensitizing agents that are activated with light to treat cancer cells. Finally, topical therapy with fluorouracil or imiquimod creams may be used to treat Bowen disease, especially for lesions that are larger than three centimeters in diameter and in situations where healing after the other treatment options would be compromised (e.g., lesions that involve the lower legs in older individuals or those with venous stasis disease).

After successful treatment, individuals should follow-up with their clinician to detect any recurrences. Follow-up time may vary between three to six months to a year, depending on the chosen treatment and the characteristics of the lesion. Because UV radiation is the main risk factor for Bowen disease and skin cancer, individuals may be advised to avoid or minimize sun exposure, use broad spectrum sunscreens daily, and wear protective clothing to protect the skin from the sun.

Bowen disease is an early form of skin cancer that has the potential to develop into an invasive squamous cell carcinoma. The main risk factor is UV exposure; therefore, sun-exposed areas like the head and neck are particularly affected. Lesions usually appear as small, well-circumscribed, red elevations of the skin with scaly plaques that grow slowly over months or years. Diagnosis involves examining the skin closely with a dermatoscope followed by a skin biopsy. Treatment options include surgery to remove the tumor. In selected cases, non-surgical options may include curettage and electrodesiccation; cryotherapy; photodynamic therapy; and topical treatment, such as chemotherapy creams.