Intraepidermal squamous cell carcinoma
Intraepidermal squamous cell carcinoma (intraepidermal SCC) is often known as Bowen disease, Bowen's disease or cutaneous squamous cell carcinoma in situ. It is a common type of skin cancer.
Squamous cell carcinoma (SCC) is a cancer derived from squamous cells, the flat cells that make up the outside layers of the skin (the epidermis). ‘In situ’ means the malignant cells are confined to cell of origin i.e., the epidermis.
The development of a lump or bleeding may indicate progression into invasive SCC and occurs in about 5% of intraepithelial SCC lesions.
What does intraepidermal SCC look like?
Intraepidermal SCC presents as one or more irregular, flat, red and scaly patches of up to several centimetres in diameter. Although intraepidermal SCC may arise on any area of skin, the lesions are most often diagnosed on sun exposed sites such as the ears, the face, the hands and the lower legs.
Rarely, intraepidermal SCC may start to grow under a nail, when it results in a red streak (erythronychia) that later may destroy the nail plate. These ungual and periungual SCC in situ are associated with human papillomvirus infection (viral warts).
|© Dr Ph Abimelec – dermatologue Used by DermNet NZ with permission|
What is the cause of intraepidermal SCC?
Intraepidermal SCC arises in aging skin. It may be caused by:
- Sun exposure: intraepidermal SCC is most often found on sun exposed sites of fair skinned individuals. This is because ultraviolet radiation damages the skin cell nucleic acids (DNA) resulting in a mutant clone of the gene p53. This sets of uncontrolled growth of the skin cells. Ultraviolet radiation also suppresses the immune response preventing recovery from this damage.
- Arsenic ingestion: this may result in multiple areas of intraepidermal SCC on the trunk and limbs some years after exposure.
- Ionising radiation: intraepidermal SCC was common on the hands of radiologists early in the 20th century.
- Human papillomavirus (HPV) infection: this rarely causes intraepidermal SCC. However, HPV infecting genital sites is the cause of vulval and penile intraepithelial neoplasia or mucosal SCC in situ.
Treatment of intraepidermal SCC
As intraepidermal SCC is confined to the surface of the skin, there are various ways to remove it.
Cryotherapy means removing a lesion by freezing it, usually with liquid nitrogen. Cryotherapy may be suitable for small, flat patches of intraepidermal SCC.
Superficial skin surgery
Superficial skin surgery refers to shave, curettage, & electrosurgery . The lesion is sliced off or scraped out, then the base is cauterised. The wound usually heals rapidly without the need for stitches.
5-Fluorouracil cream contains a cytotoxic agent. The cream may be applied to intraepidermal SCC for 4 to 12 weeks. It causes a vigorous skin reaction that may ulcerate.
Imiquimod is an immune response modifier in a cream base. Applied five times weekly for six to sixteen weeks, it will clear most patches of intraepidermal SCC but is not yet licensed for this purpose (June 2008).
Photodynamic therapy (PDT) refers to treatment with a photosensitiser (a porphyrin chemical) that is applied to the affected area prior to exposing it to a strong source of visible light. The treated area develops a "burn" and then heals over a couple of weeks or so. Metvix PDT is now available to treat superficial skin cancers in New Zealand. It appears to provide high cure rates for iintraepidermal SCC on the face or lower legs, but is not yet licensed for this purpose (June 2008).
What happens after treatment?
Intraepidermal SCC may recur months or years after treatment. It may be treated again by the same or another method.
Patients who have been treated for intraepidermal SCC are at risk of developing new lesions of intraepidermal SCC. They are also at increased risk of other skin cancers, especially squamous cell carcinoma, basal cell carcinoma and melanoma. Arrange a complete skin examination from time to time. Ask your dermatologist or GP to check any persisting or growing lumps or sores or otherwise odd-looking skin lesions. Early detection means easier treatment, and less scarring.
Protect your skin from excessive exposure to the sun. Stay indoors or under the shade in the middle of the day. Wear covering clothing. Apply broad spectrum sunscreens to exposed skin if you are outdoors for prolonged periods, especially during the summer months.
- Guidelines for Management of Bowen's Disease: update 2006 (NH Cox, DJ Eedy, CA Morton). BJD, Vol. 151, No.1, January 2007 (p11-21) – British Association of Dermatologists
On DermNet NZ:
- Best Treatments from the BMJ: clinical evidence about squamous cell carcinoma for patients
- Bowen Disease – Medscape Reference
- Bowen's disease – British Association of Dermatologists
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