The skin does not show any other changes. The lesions are usually located 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.
It does not occur anywhere else on the body. 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.
It has also been seen to develop in females taking contraceptive pills and disorders of the liver.
There is an increase in the level of melanin, large numbers of melanocytes and melanosomes and increased synthesis of tyrosinase in the affected skin.
Cumulative sun exposure and hormonal factors have been suggested.
There is a female to male predilection in a ratio of 9:1.
Risk factors of Melasma
- Asian and Hispanic origin
- Hormonal factor [occurs comoonly in pregnancy]7]
- 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 bluish tinge
- The colour may vary from tan to brown, but may be black or have a bluish tinge.
- Presentation can be centrofacial, malar or mandibular.
- Addison’s disease.
- Drug-induced photosensitivity.
- Discoid lupus erythematosus.
- Poikiloderma of Civatte
Wood’s light helps to locate the pigmentation in the dermis or epidermis.
An attempt should be made to look for endocrinal abnormalities, the presence of anaemia, gastro-intestinal infestations or liver disease and if present, these should be treated with appropriate therapeutic agents.
- Mild cases may simply require reassurance. Chloasma associated with pregnancy should resolve spontaneously within a few months but may persist
- 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 colour and can be used if hydroquinone is contra-indicated or ineffective.
- A combination of retinoic acid cream, a steroid cream and hydroquinone cream/solution has been found to produce the best results.
Prognosis of Melasama
Most cases resolve though may take a long time. Continued exposure to sunlight slows the response to treatment and may cause recurrence.