This is an accumulation of special cells – melanocytes. These cells protect us from excessive ultraviolet radiation. “For the term” mole “doctors mean a pigmented formation of a nevus. The appearance of neoplasms on the body can be an alarming signal, therefore it is necessary to carefully monitor birthmarks on the body, says Nikolai Dmitriev, dermatologist of the multidisciplinary clinic” Aloderm “, to RIA Novosti. With prolonged exposure to the sun, our skin acquires a tan – melanin, a product of these cells, from which arises the most terrible malignant tumor today – melanoma. It is so called because the rate of growth and metastasis of the tumor is one of the highest. Истoчник ria.ru There are many such pathological processes, but most often doctors distinguish uncontrolled sunburn, a large number of nevi, immunodeficiency states and a genetic predisposition, “the dermatologist explained. This cancer occurs when there is a violation of the division of melanocytes.