What causes Bowen's disease?

Bowen's disease, also called squamous cell carcinoma in situ, affects the outer layer of skin. The abnormal cells remain confined to that layer, but an untreated patch can become more invasive. Sun-exposed areas such as the face, scalp, ears, neck, forearms and hands are common sites, although it can occur on covered skin too.

Risk can be increased by cumulative sun exposure, repeated sunburn, a weakened immune system, previous radiation to the skin, or exposure to certain chemical irritants. Some lesions are associated with human papillomavirus, particularly in genital or nail-area skin. A red, scaly or crusted patch cannot be assigned a cause from appearance alone.

Arrange an appointment with a dermatologist or primary-care clinician for any persistent scaly patch, especially one that bleeds, crusts, thickens or changes. Diagnosis may require a small skin sample. Treatment is selected according to the patch's site, size, thickness and your health; options can include removing it, freezing it, prescribed cream, light-based treatment or a procedure that checks the edges.

Protect surrounding skin with shade, clothing and broad-spectrum sunscreen, and avoid picking the area. Keep a simple record of changes so you can describe its course accurately.

Book a skin assessment promptly if a patch persists or develops bleeding, an open sore, increasing pain, rapid growth or a firm raised edge. Seek urgent medical help for heavy bleeding, spreading redness with fever, or severe pain. These signs do not prove cancer, but they need timely assessment.

Ask whether the area needs a biopsy, which exposures may have contributed, what treatment fits its location, and how often you should have a full skin examination.