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.
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.
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.
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