Melanoma is one of the most malignant tumors, rapidly metastasizing by lymphogenous and hematogenous routes. It comes from cells called melanocytes. Skin melanoma develops from epidermal melanocytes of both normal skin and pigmented nevi.
Melanoma is about 10 times less common than skin cancer – it is within 1% of the total number of malignant neoplasms. The incidence of melanoma in the last time increases, in women it occurs more often than in men. The incidence of melanoma increases rapidly in the age group of 30-39 years, then there is a gradual, slow increase in the incidence of the tumor until old age.
Melanoma traditionally develops from acquired and congenital nevi and Dubrey’s melanosis.
Pigmented nevi occur in 90% of people. Depending on the skin layer from which they develop, there are epidermal-dermal, or borderline, intradermal and mixed. The most dangerous are borderline nevi. They are a well-defined nodule of black-brown, black-gray or black color with a smooth, dry surface, on which there is no hair. The nodule is flat or slightly elevated above the skin surface, painless. It has a soft-elastic texture. Sizes vary from a few millimeters to 1 cm. The borderline nevus is traditionally localized on the head, neck, palms and feet, and torso. The frequency of malignancy of mixed nevi is much lower. And from dermal nevi, melanoma develops in isolated cases.
Surgery for nevi was previously considered dangerous. This notion turned out to be wrong. It is now believed that the excision of any and even borderline nevus within healthy tissue guarantees recovery and is a reliable measure for the prevention of melanoma. Especially recommended is the removal of nevi located on the sole, foot, nail bed, in the perianal region, which are almost always borderline in their structure and are often traumatized.
The transformation of pigmented nevi into melanoma is promoted by trauma, ultraviolet radiation and hormonal changes in the body. Two subsequent factors are likely to influence the occurrence of melanoma on intact skin.
The role of trauma is beyond doubt. Approximately 40% of melanoma patients show signs of malignancy soon after an accidental or intentional injury to the pigmented nevus. Insolation is associated with a high frequency of melanomas in the southern states and regions, as well as the frequent occurrence of tumors on exposed parts of the body.
The role of endocrine influences on the development of melanoma is suggested, which rarely appear before puberty, and during puberty, pregnancy and menopause, acceleration of tumor growth is sometimes observed. In some cases, a change in hormonal status leads to inhibition and even regression of the tumor.
Unlike skin cancer, the predominant location of melanoma on the face is not observed. In almost half of the patients, the tumor occurs on the lower extremities, somewhat less frequently on the trunk (20–30%) and upper extremities (10–15%), and only in 10–20% in the head and neck.
The growth and spread of melanoma occurs by germination of surrounding tissues, lymphogenous and hematogenous metastasis.
Melanoma grows in three directions: above the skin, along its plane and in depth, subsequently growing through the layers of the skin and underlying tissues. The deeper the cords of tumor cells spread, the worse the prognosis.
Melanoma is characterized by rapid and early metastasis. Most often, metastases affect regional lymph nodes. Metastases to distant lymph nodes are less common.
Skin metastases are common. They have the appearance of small multiple, brown or black rashes slightly elevated above the level of the skin.
Hematogenous metastases can occur in any organ, but the lungs, liver, brain, and adrenal glands are most commonly affected.
- an increase in size, compaction, bulging of one of the areas or a uniform growth of a pigmented formation above the skin surface;
- strengthening, and occasionally weakening of the pigmentation of the nevus;
- bleeding, cracking or superficial ulceration with crusting;
- redness, pigmented or non-pigmented strands, infiltrated tissues surrounded by a nevus;
- the appearance of itching, burning;
- formation of satellites, enlargement of lymph nodes.
It should be taken as a rule: any nevus protruding above the surface, discolored, weeping, bleeding or causing unpleasant subjective sensations, is suspected of melanoma. You need to consult an oncologist.
Treatment of melanomas is a difficult task and should be carried out only in a specialized institution.