What we call nevus is medically called pigmented nevus or nevus cells. This is the last benign tumor of the skin. Most people have 10 to 40 moles.

Generally speaking, melanocytes are evenly distributed in the skin and are the cells that mainly produce melanin in the human body. If due to congenital or acquired factors, black cells gather into lumps or proliferate, forming moles. At this time, melanocytes are called nevus cells.

Nevus cells will become melanoma due to congenital or acquired factors. Therefore, moles and melanoma can be described as "the same root."

The congenital factors that induce malignant transformation of nevus are mainly ethnic factors and immune deficiency.

Melanoma is rare in China, but its incidence rate is among the highest in the United States. The incidence rate of white Americans is as high as 42/65438+ million per year, while the incidence rate of black Americans is only 0.8/65438+ million per year. Therefore, white people are more prone to malignant transformation of moles than colored people.

Immunodeficiency is also a factor of malignant transformation of nevus. Clinically, the proportion of senile melanoma patients is relatively large, which is related to the corresponding decline of immunity with age. Immunodeficiency is one of the important reasons for malignant nevus turning into melanoma.

Because moles grow on human epidermis, there are many external factors that will stimulate moles and lead to malignant transformation of moles. These external factors include long-term friction, ultraviolet radiation and chemical skin pollution.

Dot mole can promote the canceration of nevus.

Many people will use lasers to remove moles, because they are ugly or out of superstition. But laser nevus removal may cause cancer, which is related to multiple laser nevus removal. Invasive laser nevus removal can not only remove melanin, but also remove melanocytes. In order to reduce the area of trauma, doctors will be more cautious. If the laser is excessive, it will easily lead to scars; If the laser is not thorough, there are residual nevus cells, and the nevus will grow again. So many people will do invasive lasers many times.

Repeated stimulation may activate nevus cells and accelerate the malignant transformation of benign nevus. In addition, laser irradiation of basal cells may have no pigment, which increases the risk of basal cell canceration.

If melanoma is unfortunately mistaken for a benign nevus, laser resection will further aggravate it.

Five "signals" of malignant transformation of nevus

In the process of malignant transformation into melanoma, without careful observation, moles are not much different from ordinary moles and are easily overlooked. But as long as you look closely, you can still see the difference.

Before the nevus becomes cancerous, the following symptoms will appear:

1. Comparison rules of normal nevus. If moles start to become jagged and jagged, you should be on your guard.

2. variegated color is also a signal of malignant change. Melanoma with freckles and superficial spread usually appears brown or black with red, white or blue. Blue is more ominous.

3. The surrounding skin appears edema or loss of luster, turning white or gray.

4. Nevus become unsmooth and rough, accompanied by scaly or flaky desquamation and sometimes oozing blood.

5. Local itching, burning pain, or pain when pressing. When the nevus continues to become malignant and develops into ulcerative lesions, there will be symptoms of oozing fluid and blood, and the tingling or burning sensation is more obvious.

Melanoma is rare in Asian population. However, external stimuli such as laser nevus removal will still increase its risk, so be more careful.