Tumours of the skin

A wide range of tumours, both benign and malignant, are found in skin. Benign skin lesions such as seborrhoeic keratoses and skin tags are often just a cosmetic nuisance, but some benign skin lesions can be a component of diseases with serious medical consequences, e.g. neurofibromatosis or LEOPARD syndrome.

Exposure to ultraviolet light (UVL) is a major factor leading to the development of both benign lesions, e.g. melanocytic naevi, and most skin cancers. Changes in dress style, increased travel abroad, use of sun tanning salons (sunbeds), and the depletion of the ozone layer have all contributed to increased exposure to UVL.

Skin cancer is the most common human cancer and its incidence continues to increase. It most commonly affects older, fair-skinned individuals who have had either acute intermittent exposure to UVL or chronic UVL exposure. Organ transplant recipients have a 200-fold increased risk of squamous cell carcinoma. About 2% of patients who develop skin cancer have a genetic predisposition, e.g. Gorlin’s syndrome in basal cell carcinoma (BCC) and familial melanoma syndromes in malignant melanoma. Mutations in the PTCH gene cause Gorlin’s syndrome, and loss of heterozygosity at that locus is also present in most sporadic BCC.

Nonmelanoma skin cancer is rarely fatal, but can cause a lot of morbidity. Malignant melanoma is a deadly skin cancer which is the 2nd most common cancer (excluding nonmelanoma skin cancer) in young women. Over the last 20 years, its incidence has been increasing faster than any other cancer, with an approximate doubling of rates every 10 years in countries with largely white populations. Early detection and excision of melanoma is the best way to reduce mortality, as there is no curative treatment for metastatic malignant melanoma.