Malignant melanoma: diagnosis, treatment and cancer stem cells.

Malignant melanoma represents a neoplasm stemming from melanocytes or the cells that develop from melanocytes. Melanocytes, pigment-producing cells, arise from the neural crest and migrate to their final destinations in the skin, uveal tract, meninges, and mucosa. Most melanocytes are found at the epidermal-dermal junction of the skin, and the vast majority of melanocytes arise from cutaneous sites. Cancerous growths develop when unrepaired DNA damage to skin cells (most often caused by ultraviolet radiation from sunshine or tanning beds) triggers mutations (genetic defects) that lead the skin cells to multiply rapidly and form malignant tumours. Malignant tumours consist of heterogeneous populations of tumour cells. Cancer stem cells (CSC) represent a population of cells within a tumour with highly tumorigenic and chemoresistant properties. These cells may be identified by the expression of CSC markers and also by functional assays as tumour-initiating properties in vivo, high aldehyde dehydrogenase activity tested by Aldefluor assay. There are several key stem cells markers specified for malignant melanoma: CD20, CD133, ABCB5, CD271 and ALDH1A. The review provides a detailed overview of risk factors, diagnosis, treatment possibilities and specific properties of cancer stem cells in malignant melanoma.