Different Dermatological Approaches in Treatment of Melasma: A Split Face Randomized Clinical Trial

Melasma is a common, acquired, circumscribed hypermelanosis of the sun-exposed skin, It presents as symmetric, hyperpigmented macules having irregular, serrated, and geographic borders , The most common locations are the cheeks, upper lips, the chin and the forehead, but other sun-exposed areas may also be occasionally involved .

Studies has indicated the role of several risk factors such as genetics, sunlight, age, gender, hormones, pregnancy, thyroid dysfunction, cosmetics and medications .

Histologic features of melasma include an increase in the content of both epidermal and dermal melanin, but the quantity varies with the intensity of hyperpigmentation. In addition, most studies show no quantitative increase in melanocytes; however, the cells are enlarged with prominent and elongated dendrites and more abundant melanosomes. Additional features of the involved skin include solar elastosis and increased mast cells, dermal blood vessels, and expression of vascular endothelial growth factor.

Commonly used topical agents for the treatment of melasma include hydroquinone, azelaic acid, kojic acid, glycolic acid, salicylic acid and tretinoin. Of these treatments, hydroquinone remains the gold standard .Second-line treatments, such as chemical peels and lasers, are efficacious in some patients .

Chemical peeling is the application of a chemical agent to the skin, which causes the controlled destruction of a part or of the entire epidermis with or without the dermis, leading to exfoliation and removal of superficial lesions, followed by regeneration of new epidermal and dermal tissues [khunger, 2008]. The mechanism of action in melasma is the removal of unwanted melanin via controlled chemical burn of the skin .