Melanoma is one of the most malignant tumors, rapidly metastasizing with lymphogenous and hematogenous pathogens. It comes from cells called melanocytes. Melanoma of the skin develops from the epidermal melanocytes of both normal skin and pigmented nevi.
Melanoma occurs about 10 times less often than skin cancer - it accounts for about 1% of the total number of malignant neoplasms. The incidence of melanoma has recently increased, in women it occurs more often than in men. The incidence of melanoma sharply increases in the age group of 30-39 years, then there is a gradual, slow increase in the incidence of the tumor until old age, according to the Internet publication for girls and women from 14 to 35 years old Pannochka. net Preceding diseases Melanoma usually develops from acquired and congenital nevuses and melanosis of Dubreia.
Pigmentary nevuses are found in 90% of people. Depending on the layer of skin from which they develop, distinguish epidermo-dermal, or borderline, intradermal and mixed. The most dangerous border nevuses. They are a clearly defined bundle of black-brown, black-gray or black with a smooth dry surface, on which there is no hair. Nodule flat or slightly rising above the surface of the skin, painless. Has a soft-elastic consistency. Dimensions vary from a few millimeters to 1 centimeter. The border nevus is usually located on the head, neck, palms and feet, trunk. The frequency of malignancy of mixed nevi is much lower. And from dermal nevuses melanoma develops in isolated cases.
Surgical intervention with nevi was previously considered dangerous. This view was erroneous. Currently, it is believed that excision of any and even borderline nevus within the healthy tissue guarantees recovery and is a reliable measure for the prevention of melanoma. Especially recommended removal of nevi, located on the sole, foot, nail bed, in the perianal area, which are almost always structurally borderline and are often subject to injury.
Predisposing factors The transformation of pigmented nevuses into melanoma is facilitated by trauma, ultraviolet irradiation and hormonal changes in the body. The last two factors may have an effect on the onset of melanoma on unchanged skin.
The role of injury is beyond doubt. Approximately 40% of melanoma patients show signs of malignancy soon after accidental or intentional trauma to pigment nevus. With insolation, a greater frequency is associated with melanomas in southern countries and regions, as well as the frequent occurrence of tumors on open parts of the body.
Assume the role of endocrine influences on the development of melanoma, which is extremely rare before puberty, and during puberty, pregnancy and menopause, there is sometimes an acceleration of tumor growth. In some cases, a change in the hormonal status leads to inhibition and even regression of the tumor.
Localization, growth and distribution In contrast to skin cancer, the preferred location of melanoma on the face is not observed. Almost half of the patients have a tumor on the lower extremities, somewhat less often on the trunk (20-30%) and the upper limbs (10-15%) and only 10-20% in the head and neck.
Growth and spread of melanoma occur through the germination of surrounding tissues, lymphogenous and hematogenous metastasis.
Melanoma grows in three directions: above the skin, along its surface and deep into, successively growing layers of skin and underlying tissues. The deeper the strains of tumor cells spread, the worse the prognosis.
Metastasis Melanoma is characterized by rapid and early metastasis. Most often, regional lymph nodes are affected by metastases. Metastases to distant lymph nodes are less common.
Often there are metastases in the skin. They have the appearance of small multiple, slightly rising above the skin level of rashes brown or black.
Hematogenous metastases can occur in any organ, but most commonly affect the lungs, liver, brain and adrenal glands.
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