Melasma is an acquired hypermelanosis of sun-exposed areas presenting as symmetrically distributed hyperpigmented macules.
These macules may be punctate or confluent.
Melasma or chloasma is also called the mask of pregnancy. In this condition, there are asymptomatic, very superficial-looking macular areas of brownish pigmentation.
The skin does not show any other changes. The lesions are usually located over the bridge of the nose, both the cheeks, the upper lip, and the forehead. On the forehead, a linear area just above the eyebrows is frequently involved, while an area of the upper lip below the nose and skin around the eyes are as a rule spared.
Most commonly, the lesions appear during pregnancy, but they have also been seen in unmarried girls as well as males. If the lesions appear during pregnancy, the lesions may persist even after delivery. The cause of this pigmentation is not known.
The is a female to the male occurrence is in a ratio of 9:1.
Melasma present in 8.8%-40% among females of different origins
Melasma is especially common in Latinos and Asians, from areas of the world with intense sun exposure.
Melasma is rare before puberty. It is present in 15-50% of pregnant patients
Pathophysiology of Melasma
The pathophysiology of melasma is not clear.
Most likely contributing factors are genetic and hormonal. Ultraviolet radiation is another influencer.
Melasma is much more common in women than in men. Brown skin people are more prone to develop this.
Following observations suggest a hormonal role
- Melasma occurs more frequently in females than in males
- Commonly develops or worsens during pregnancy [Called mask of pregnancy]
- Estrogen, progesterone, and melanocyte-stimulating hormone (MSH) increase during the third trimester
- Worsens with use of contraceptive pills
- The expression of estrogen receptors appears to be up-regulated in melasma lesion
Postmenopausal women who are given progesterone can develop melasma.
Exposure to Sun
The exposure to sunlight [actually ultraviolet radiation] causes increased production of alpha-melanocyte-stimulating hormone, corticotropin, interleukin 1 and endothelin 1.
These lead to an increase in melanin production by intraepidermal melanocytes.
Ultraviolet radiation also causes peroxidation of lipids in cell membranes, leading to the generation of free radicals, which could stimulate melanocytes to produce excess melanin.
Both UV-A and visible radiation 320-700nm] and UV-B radiation (290-320 nm) can lead to the changes
Fibroblasts located in the dermal layer of the skin may also contribute.
Types of Melasma
Mainly three patterns of melasma are seen depending on the involvement.
- Forehead, cheeks, nose, upper lip, and chin.
- Nose and the cheeks.
- Ramus of the mandible area
- Very rare pattern
- In native American women receiving exogenous progesterone
Risk factors of Melasma
- Asian and Hispanic origin
- Hormonal factor [occurs commonly in pregnancy]
- Sun exposure
- Family history
Clinical Presentation of Melasma
- Patients usually complain of gradual-onset areas of dark skin, usually symmetrical. The color varies from tan to brown but may be black or have a bluish tinge.
- The color may vary from tan to brown, but maybe black or have a bluish tinge.
- Presentation can be centrofacial, malar or mandibular.
The patient, typically a female complains about progressive hyperpigmentation of the face. It could be related to pregnancy or the use of oral contraceptive pills.
Face especially cheeks, upper lip, chin and forehead are exposed to sunlight more and melasma is more common.
Long term exposure to sunlight worsens the condition though due to the insidious nature of the condition and its progression correlation may be missed by the patient.
The hyperpigmentation usually is tan to brown. Blue or black may be evident in patients with dermal melasma. The distribution is one of three patterns.
- Addison’s disease
- Drug-induced photosensitivity
- Discoid lupus erythematosus
- Poikiloderma of Civatte
- Acanthosis Nigricans
No laboratory tests are needed for melasma usually. The patient may be checked for thyroid functions.
Wood lamp examination usually helps to localize the pigment to the epidermis or the dermis.
In many cases, it may be found in both locations.
In individuals with dark-brown skin, the pigment may not be localized and classified as indeterminate.
An attempt should be made to look for endocrinal abnormalities, the presence of anemia, gastrointestinal infestations or liver disease.
Treatment of Melasma
The resolution of melasma with treatment may take many months. The pigment develops gradually and resolves gradually.
Resistant cases are often associated with continued sunlight exposure.
Mild cases may simply require reassurance. Chloasma associated with pregnancy should resolve spontaneously within a few months but may persist.
Topical depigmentation agents and avoidance of sun are mainstay of the treatment. Estrogen exposure if any [i.e. contraceptive pills] is stopped.
A 2-5 percent solution or cream of hydroquinone for three to six months may reduce the pigmentation. In some cases, there may be a tendency for recurrence when the treatment is stopped. In such cases, the treatment can be continued to maintain the improvement.
Topical corticosteroids especially clobetasol propionate can also reduce the skin color and can be used if hydroquinone is contra-indicated or ineffective.
A combination of retinoic acid cream, steroid cream, and hydroquinone cream/solution has been found to produce the best results.
After treatment, for further prevention avoidance of sunlight and use of sunscreens with SPF 50+.
Hydroquinone inhibits tyrosinase, the enzyme in the pathway of melanin synthesis. Its cytotoxic metabolites may interfere with melanocyte function and viability.
It is applied in cream form or as an alcohol-based solution [2%-4%]
Though a matter of intense discussion, all concerns regarding its potential carcinogenic effects have yet to be proven substantially.
Retinoids are derivatives of vitamin A. These lead to
- Increased keratinocyte turnover
- Decreased melanocyte activity
- Increase the permeability of the epidermis [allow better penetration of other drugs.]
They can be used as topical monotherapy or in combination as they allow better penetration of other drugs.
These can be combined with topical hydroxyquinone or steroids or both.
Mild skin irritation, photosensitivity, and paradoxical hyperpigmentation are known side-effects. Retinoids are known to have a teratogenic effect.
Azelaic acid [20% cream] has a mechanism of action is similar to that of hydroquinone but azelaic acid targets hyperactive melanocytes. That means it will not lighten the skin as it would spare the skin with normally functioning melanocytes.
Skin irritation is the primary side effect.
Peels and Lasers
Chemical peels are used as second line therapies only as results are not predictable. Therefore, they should only be used when at least one skin-lightening agent has failed.
Epidermal necrosis, postinflammatory hyperpigmentation, and hypertrophic scars are common side effects.
Skin peels use glycolic or salicylic acid–based compounds. These are believed to increase the turnover of hyperpigmented keratinocytes.
These are first applied on monthly and then progressed to a weekly basis.
Use of depigmentation agents along with peels provide better results.
Treatment with peels requires a close watch for the development of pigmentation in the surrounding skin.
The role of lasers in melasma is not clear and are often associated with non-satisfactory cosmetic results.
Sun Light Exposure
Treatment often fails if sunlight is not avoided. Staying in shade, using hats and use of sunscreeens [that cover both UV-B, UV-A and visible light] are the measures fro protection from sunlight.
Prognosis of Melasma
Most cases resolve though may take a long time. Continued exposure to sunlight slows the response to treatment and may cause recurrence.
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