freckle
Introduction
Introduction
Cause
Cause
1. "Freckles" are caused by genetics:
The "Freckle Genetics" increases the tyrosinase activity of the basal layer under ultraviolet light, forming melanin, which is also a freckle, also called a genetic plaque, which is an innate fixation in the fetal period. Hereditary freckles are characterized by plaques and invisible plaques. The plaques begin to form at about 6-12 years old and reach peaks around 18 years old. The invisible plaques are mostly reflected in the face after the pregnancy, which is why some people have freckles. For the reason of congenital freckles and acquired freckles, in fact, the endocrine of pregnant women will change a lot after pregnancy, which will stimulate the hidden freckles to erupt, rather than saying that their freckles are long after. As long as freckles are caused by genetics. The inheritance of freckles is inherited by generations, which is why some parents do not have freckles, and their children have freckles. Although the freckles of one or both parents did not appear, the freckle genetics carried by one or both of them were passed on to the child.
2. Exposure to the sun:
Ultraviolet light in the sun stimulates the pigment cells in the subcutaneous area to produce a large amount of melanin pigment. On the other hand, the normal metabolic function of damaged skin cells makes melanin unable to be discharged smoothly and remains on the skin, even in the dermis. Therefore, excessive sun exposure will increase and deepen freckles, but in winter, freckles will gradually fade.
Examine
an examination
Related inspection
Skin lesion
Features:
(1) When the age of 4 to 5 years old begins to develop, the rash increases with age, and the rash after puberty generally does not increase.
(2) In summer, the shape of the rash becomes larger, the color is deepened, and the number is increased.
(3) No symptoms and systemic symptoms.
Signs:
(1) It is good to be exposed to the exposed parts, and it is more common in the face, neck, double upper limbs and the back of the hand.
(2) The rash is a large black rash from the needle to the mung bean, which is dense and dense, does not fuse with each other, and is symmetrically distributed.
Diagnosis
Differential diagnosis
Differential diagnosis
1, crotch brown cyan: symmetrical distribution of black and gray spots, the boundaries are obvious, the number is about 10-20, more common in women. The beauty salon is called a dermal spot or plaque. The cause is unclear.
2, freckle-like sputum: the age of onset is about one year old or two years old, the color is deeper than freckles, and has nothing to do with sun exposure, no summer heavy winter light changes can occur in any part. Pathology showed an increase in the number of melanocytes. On the normal side, it is generally dense.
3, color dry skin disease: freckle-like pigment spots around the telangiectasia, pigment spots vary in size, uneven depth, uneven distribution. See atrophic spots, photosensitive.
4, face in the middle of freckles-like sputum: rare, often in the first year of age, brown concentrated in the center of the face with other deformities, such as epilepsy, low intelligence.
5, pigmentation - intestinal polyps syndrome: pigment spots are black, cheek mucosa more common, not affected by sunlight, often accompanied by polyps.
6, chloasma: light brown to dark brown pigmentation spots symmetrically distributed facial, does not involve the eyelids and oral cavity. The edges are clear or diffuse, sometimes butterfly-winged. More common in women of childbearing age.
