Skin cancers develop from particular structures of the skin and therefore, they form a very diverse group. They may originate from:
- skin appendages (hair follicles, sebaceous glands, sweat glands),
- melanin-producing cells,
- mesenchymal structures (fibrous tissue, adipose tissue, blood vessels and glands, muscles),
- nerves and cells of the neuroendocrine system,
- the cells of the lymphatic system;
Classification of proliferative skin lesions:
1) - nevi (birthmarks) - structural, inborn irregularities of the epidermis and dermis, which may appear at birth, during the first years of life or, in some cases, up to 2nd to 4th life decade,
- true cysts - structures involving empty or filled space, having a distinct membrane and division,
- pseudocysts: do not have a distinct membrane,
3) pre-cancerous growths (premalignant) - skin lesions that in particular percentage of cases develop into malignant tumours (e.g. actinic keratosis, cutaneous horn, Bowen's disease, erythroplasia of Queyrat, leukoplakia, dysplastic nevus, lentigo maligna),
4) - benign tumour - skin growth that develops locally, without invading and destroying the surrounding tissues (e.g.epithelioma, adenoma),
5) cancers - growths that intensively spread an destroy local tissues, in some cases, spreading to more distant parts of the body through the lymphatic system or bloodstream (e.g. cancer, melanoma, carcoma);
Skin cancer is the most common of all cancers in people of white race. This represents approximately 97% of all skin cancers and about 30% of all malignant tumours. The most often occurring cancer of all skin cancers is basal cell carcinoma (BCC). It is five times more frequent than squamous cell carcinoma (SCC). Totally, the incidence of skin cancer in Poland, in 2005, was more than 4,300 of new cases among women and nearly 4,000 among men. In terms of the incidence of malignant tumours, the fact placed the skin cancer, respectively, on the 3rd and 5th place.
Malignant melanoma represents 5-7% of skin cancers. In Poland, in 2003, the incidence was 3,8:100 000, which ranks the melanoma as 16th of all types of cancers. The mortality rate was calculated 1,5:100 000 for women and 2:100 000 for men. The world's highest incidence of melanoma is in Australia, which is now 28,9:100 000 among men and 25,3:100 000 among women.