1. 白 癜 风 vitiligo

2. Definition Vitiligo is a condition that causes depigmentation of parts of the skin. It occurs when skin pigment cells die or are unable to function. depigmentationskin pigment cells The incidence worldwide is less than 1%, with some populations averaging between 2-3%

3. causes What causes vitiligo? Vitiligo develops when cells called melanocytes (meh-lan- o-sites) die. These cells give our skin and hair color. Scientists do not completely understand why these cells die. One type of vitiligo, non-segmental vitiligo, may be an autoimmune disease. An autoimmune disease develops when the body mistakes a part of itself as foreign. If the body mistakes these cells as foreigners, it will attack and kill these cells. Vitiligo is sometimes associated with autoimmune and inflammatory diseases, commonly thyroid overexpression and underexpressionautoimmune inflammatory diseasesthyroid

4. Studies suggest that the other type of vitiligo, segmental vitiligo, has a different cause. This type seems to develop when something in the body’s nervous system goes awry.

5. causes Variations in genes that are part of the immune system or part of melanocytes have both been associated with vitiligo the gene TYR, which makes the skin pigment cell (melanocyte) more susceptible to the immune system in vitiligo, The major alleles of TYR are associated with vitiligo, and the minor alleles are associated with malignant melanomaskin pigment cell PTPN22, was associated with generalized vitiligo (protein tyrosine phosphatase nonreceptor-22 gene ) PTPN22

6. A genomewide association studies found approximately 36 independent susceptibility loci for generalized vitiligo. Some patients had vitiligo alone; others had generalized vitiligo with other autoimmune diseases. Most loci were associated with both forms.

7. Classification Classification attempts to quantify vitiligo have been analyzed as being somewhat inconsistent, while recent consensus have agreed to a system of segmental vitiligo (SV) and non-segmental vitiligo (NSV).

8. Non-segmental Classes of non-segmental vitiligo include the following: Generalized Vitiligo: the most common pattern, wide and randomly distributed areas of depigmentation Universal Vitiligo: depigmentation encompasses most of the body Focal Vitiligo: one or a few scattered macules in one area, most common in children Acrofacial Vitiligo: fingers and periorificial areas Mucosal Vitiligo: depigmentation of only the mucous membranes

9. Segmental Segmental vitiligo (SV) differs in appearance, cause and prevalence from associated illnesses. Its treatment is different from that of NSV. It tends to affect areas of skin that are associated with dorsal roots from the spinal cord and is most often unilateral. It spreads much more rapidly than NSV and, without treatment, it is much more stable/static in course and is not associated with auto-immune diseases. causedorsal rootsspinal cord

10. Segmental vitiligo (SV) It tends to affect areas of skin that are associated with dorsal roots from the spinal cord and is most often unilateral.dorsal rootsspinal cord

11. Focal Vitiligo: one or a few scattered macules in one area, most common in children

12. Mucosal Vitiligo: depigmentation of only the mucous membranes

13. Generalized Vitiligo: the most common pattern, wide and randomly distributed areas of depigmentation

14. Acrofacial Vitiligo: fingers and periorificial areas

15. Universal Vitiligo: depigmentation encompasses most of the body

16. 毛发受累

17. Diagnosis A black light (also referred to as a UVA light, Wood's lamp, or simply ultraviolet light) can be used in the early phase of this disease for identification and to determine effectiveness of treatment. Skin with vitiligo, when exposed to a black light, will glow blue. In contrast, healthy skin will have no reaction. Wood's lampultraviolet light

18. Treatment Topical applied steroids There are many treatments for vitiligo with the best evidence for applied steroids and the combination of ultraviolet light in combination with creamssteroidsultraviolet light

19. Immune mediators Tentative evidence supports a role for tacrolimus. There is tentative short term evidence for pimecrolimus but long term data is missing. tacrolimuspimecrolimus

20. Phototherapy Exposing the skin to UVB light from UVB lamps is the most common treatment for vitiligo. Both UVB broadband and UVB narrowband lamps can be used, but narrowband ultraviolet picked around 311 nm is the choice Ultraviolet light (UVA) treatments are normally carried out in a hospital clinic. Psoralen and ultraviolet A light (PUVA) treatment involves taking a drug that increases the skin's sensitivity to ultraviolet light, then exposing the skin to high doses of UVA light.UVAPsoralenPUVA

21. excimer laser 准分子激光 Patient may sit in a light box or receive excimer laser 准分子激光 treatments. Light box used to treat widespread vitiligo; laser used to treat small area. Works best on the face; least effective on hands and feet. Effective for many patients; about 70 percent see results with excimer laser.

22. Skin camouflage In mild cases, vitiligo patches can be hidden with makeup or other cosmetic camouflage solutions.cosmetic camouflage

23. Transplanting melanocytes a number of transplantation techniques has been developed, including transplantation of melanocyte precursors derived from hair follicles.

24. De-pigmenting In cases of extensive vitiligo the option to de- pigment the unaffected skin with topical drugs like monobenzone 莫诺苯宗, mequinol 对甲氧 基苯酚, or hydroquinone 氢醌 may be considered to render the skin an even colour. The removal of all the skin pigment with monobenzone is permanent and vigorous. Sun- safety must be adhered to for life to avoid severe sun burn and melanomas. Depigmentation takes about a year to completemonobenzonemequinolhydroquinone monobenzonesun burnmelanomas

25. 黑素细胞模式图

26. 黄褐斑 chloasma melasma

27. Definiton Melasma (also known as Chloasma faciei, or the mask of pregnancy when present in pregnant women) is a tan or dark skin discoloration. Although it can affect anyone, melasma is particularly common in women, especially pregnant women and those who are taking oral or patch contraceptives or hormone replacement therapy (HRT) medications.pregnant women

28. Causes Melasma is thought to be the stimulation of melanocytes by the female sex hormones estrogen and progesterone to produce more melanin pigments when the skin is exposed to sun. Women with a light brown skin type who are living in regions with intense sun exposure are particularly susceptible to developing this condition.melanocytesestrogenprogesterone melanin Genetic predisposition is also a major factor in determining whether someone will develop melasma. The incidence of melasma also increases in patients with thyroid disease.thyroid disease It is thought that the overproduction of melanocyte-stimulating hormone (MSH) brought on by stress can cause outbreaks of this condition.melanocyte-stimulating hormone Other rare causes of melasma include allergic reaction to medications and cosmetics.

29. 临床表现 The symptoms of melasma are dark, irregular well demarcated hyperpigmented macules to patches commonly found on the upper cheek, nose, lips, upper lip, and forehead. These patches often develop gradually over time. Melasma does not cause any other symptoms beyond the cosmetic discoloration. Melasma is also common in pre-menopausal women. It is thought to be enhanced by surges in certain hormones.

32. Diagnosis Melasma is usually diagnosed visually or with assistance of a Wood's lamp (340 - 400 nm wavelength). Under Wood's lamp, excess melanin in the epidermis can be distinguished from that of the dermis.Wood's lamp melanin

33. Treatment The discoloration usually disappears spontaneously over a period of several months after giving birth or stopping the oral contraceptives or hormone replacement therapy. Treatments are often ineffective as it comes back with continued exposure to the sun. Treatments to hasten the fading of the discolored patches include:

34. Topical depigmenting agents, such as hydroquinone (HQ) either in over-the-counter (2%) or prescription (4%) strength. HQ is a chemical that inhibits tyrosinase, an enzyme involved in the production of melanin. hydroquinonemelanin Tretinoin, an acid that increases skin cell (keratinocyte) turnover. This treatment cannot be used during pregnancy. Tretinoinacid

35. Azelaic acid (20%), thought to decrease the activity of melanocytes. Azelaic acid Chemical peels. Chemical peels Microdermabrasion to dermabrasion (light to deep). Galvanic or ultrasound facials with a combination of a topical crème/gel. Either in an aesthetician's office or as a home massager unit. Laser and IPL Oral Tranexamic acid has shown to provide rapid and sustained lightening in melasma by decreasing melanogenesis in epidermal melanocytes

36. In all of these treatments the effects are gradual and a strict avoidance of sunlight is required. The use of broad-spectrum sunscreens with physical blockers, such as titanium dioxide and zinc dioxide is preferred over that with only chemical blockers. This is because UV-A, UV-B and visible lights are all capable of stimulating pigment production.pigment Patients should avoid other precipitants including hormonal triggers. Cosmetic camouflage can also be used to hide melasma. Cosmetic camouflage