What Is Bowen's Disease?
Bowen's disease is squamous cell carcinoma in situ — meaning the abnormal cells are confined entirely to the epidermis (the outer layer of skin) and have not invaded through the basement membrane into the deeper tissue. It is, in effect, the earliest possible stage of squamous cell carcinoma. Left untreated, a small proportion of cases (estimated at around 3–5%) progress to invasive squamous cell carcinoma over time, which is why treatment is generally recommended.
Causes & Risk Factors
- Cumulative UV exposure — the most common cause
- Increasing age
- Immunosuppression
- Historically, arsenic exposure was a recognised cause, though this is now rare in the UK
- Human papillomavirus (HPV) infection, particularly for lesions in the genital area
Signs to Look For
Bowen's disease typically presents as a slow-growing, well-defined, scaly or crusted red or pink patch, often several centimetres across. It is most common on the lower legs, particularly in older women, but can occur on any sun-exposed skin. It grows very slowly, often over years, and can be mistaken for eczema or psoriasis if not biopsied.
Diagnosis
A biopsy is usually taken to confirm the diagnosis and to exclude invasive squamous cell carcinoma, which can sometimes coexist within or beneath an area of Bowen's disease.
Treatment Options
Several effective treatments are available, and the right choice depends on the size, site, and number of lesions, as well as patient preference:
- Cryotherapy — freezing the lesion with liquid nitrogen; effective for smaller, well-defined patches
- Topical 5-fluorouracil (5-FU) — a chemotherapy cream applied over several weeks, effective for larger or multiple lesions, with an expected inflammatory reaction as it works
- Topical imiquimod — an immune-stimulating cream, an alternative topical option
- Curettage and cautery — scraping away the abnormal skin under local anaesthetic
- Photodynamic therapy — applying a light-sensitising cream followed by exposure to a specific light source, useful for larger areas or cosmetically sensitive sites
- Surgical excision — considered where there is any concern about invasive disease, or for lesions that have not responded to other treatments
Prognosis
The prognosis for treated Bowen's disease is excellent. Because new patches can develop over time, particularly in patients with significant cumulative sun exposure, ongoing skin awareness is worthwhile even after successful treatment.