Dermatology Associates of the Bay Area

Squamous Cell Carcinoma

Squamous Cell in Situ (Bowen's Disease)

Squamous cell carcinoma in situ or "SCC in situ" is a type of superficial skin cancer due to the cancerous growth of squamous cells. It is also referred to as Bowen's disease.

The cancerous cells of SCC in situ grow only on the topmost surface of the skin. This differs from other invasive forms of squamous cell cancer that grow deeper in the skin and which are more difficult to treat.

Left untreated, SCC in situ grows larger and may eventually develop into invasive squamous cell carcinoma. SCC in situ appears on areas that have received excessive sun exposure, such as the top of the head, ears, nose and shoulders. These are the same areas where actinic keratoses (AKs) usually appear. In fact, actinic keratosis lesions are thought to be a precancerous form of squamous cell carcinoma.

The skin lesions of SCC in situ are usually red and scaly, but they can appear brown colored. A skin biopsy must usually be performed to confirm the diagnosis since the skin lesion can be mistaken for other skin conditions.

Treatment of Squamous Cell Carcinoma in Situ

Squamous cell carcinoma in situ is usually removed by surgical excision. Your doctor will recommend a procedure based on the size and location of the skin lesion, your response to past treatments, and personal preferences.

SCC in situ can be scraped off with curettage and cautery, frozen with cryotherapy, or burned off with a laser or photodynamic therapy (PDT). All of these approaches will result in skin changes and risk scarring.

Mohs surgery may be recommended if the lesion is large or in a highly visible location, such as the face.

Topical medications may also be prescribed for use alone or in combination with surgical excision. 5-FU (Efudex®, Carac®) is a topical chemotherapy and imiquimod activates the body's own immune system. Both medications can result in significant skin inflammation during treatment.

Those who have been diagnosed with SCC in situ are likely to experience a recurrence of squamous cell carcinoma and are at greater risk of developing other skin cancers. For this reason, it is important to perform regular skin self exams and see your doctor regularly for skin cancer checks.