2, moles can occur in the skin and mucous membranes of any part of the body, both congenital and acquired. Its shape is flat or slightly raised macula or maculopapule, and it can also be hemispherical, papilloma-like or pedicled. Its surface is smooth, hairy or hairless, and the number can be single, several to dozens.
Because of the different types and contents of pigments in nevus cells, nevus can be brown, brown, blue-black, black or dark brown, and pigmented nevus is mostly skin color.
3. Spots are generally caused by different constitutions or by subordinates (such as ultraviolet rays and endocrine disorders). ). Its essence is that melanin is deposited in the basal layer of the skin due to the mutation or damage of human melanin gene.
There are many kinds of spots of different shapes and sizes. In contrast, moles are deeper, protruding from the skin, and spots are shallower.
Extended data:
Several common spots on the face
1, freckle removing
Freckles are punctate, granular and clear, and do not adhere. Small to the tip of the needle, large to brown, light brown and dark brown, often appearing on the forehead, nose and cheeks. It will change with the season, and physical reasons will affect its deepening (staying up late, abnormal endocrine routine, high pressure, etc. ).)
Dominant, starting from the age of six to 12, reaching a peak around 18. Recessive, mostly appearing on the face after pregnancy. As long as it is freckles, it is caused by genes, including atavism.
Every freckle is a genetic disease that causes it to exist in the basal layer of skin in solid form. The gene of freckles is enhanced by ultraviolet radiation to form pigment, that is, freckles.
2. Freckle nevus
Freckle-like nevus is a kind of brown mottled lesion very similar to freckles, which is characterized by scattered light brown or dark brown spots, flush with the skin epidermis or slightly raised. It can occur at the junction of skin, skin and mucosa in any part of the body. Skin lesions often occur on the face, neck, shoulders and back of hands. The color is darker than freckles, and freckles can appear anywhere, which has nothing to do with sun exposure. Under normal circumstances, it is usually dense and mostly distributed in local sheets.
3, chloasma
Chloasma is the accumulation of free pigments in the bottom layer of skin. Exfoliation is a common facial pigmentation disease. Due to different parts, it can be divided into liver spots, butterfly spots, sexual spots and upper lip spots. It is characterized by unclear edge of diffuse pigment, and its color is light yellow, dark yellow and brown.
4, dermal spots
Dermal spots are pigmentation or pigmentation and the residue of lead and mercury toxins in the dermis. Subcutaneous fibrous tissue necrosis, dermal pigment aggregation. Also known as brownish-blue nevus. The shape is granular, flaky and foggy. The color is yellow brown, blue brown, dark brown or purple brown. It is distributed in bilateral zygomatic region, temporal region, forehead, nose and infraorbital region. Bilateral symmetry, about 8-20, light in winter and heavy in summer, deepened when the sun and sleep are insufficient.
References:
Baidu encyclopedia-nevus
Baidu encyclopedia-mottled