Melasma is an acquired pigmentary disorder of the face. It is a symmetrical acquired hypermelanosis with slow progression, irregular coloration and irregular outline. It typically affects sun-exposed areas on the face and presents as symmetric brownish macules and patches coalescing in a reticular pattern. Melasma is most prevalent among young to middle aged women with darker (Asian African or Middle Eastern) skin phototypes1 but can occur in lighter, western skin types as well. An estimated 6 million people in the US and 45-50 million people worldwide are affected by melasma with men comprising 10% of the affected population. Oral contraceptive pills, estrogen replacement therapy, ovarian tumors, ovarian dysfunction and thyroid dysfunction have been shown to induce melasma, suggesting a role for hormonal changes in melasma pathogenesis.
Studies assessing histology of the diseases have identified that melanin increases in the epidermis, dermis, or both. Melanocytes show increased activity leading to increased formation of melanosomes, their melanization, and transfer to the superficial epidermis and dermis layers. 3 Keratinocytes and fibroblasts in the dermis have also been found to communicate with each other to regulate the function and phenotype of the skin. Besides the genetic make-up, the racial and ethnic differences in skin color depend upon other intrinsic and extrinsic factors (facultative pigmentation). Endocrine factors such as estrogen, α- melanocyte-stimulating hormone, adrenocorticotropic hormone, paracrine and autocrine factors, the ultraviolet radiation (UV-R) exposure, vitamin D, may all enhance melanogenesis. Some reports show increased angiogenesis and VEGF (vascular endothelial growth factor) level at the melasma area as well.4 Most of melasma lesions are epidermal type that can be treated efficiently by using 755nm wavelength with microseconds pulse duration.
Recommended Treatment Settings
GentleMax Pro is a dual wavelength, long pulse laser platform providing 755 nm Alexandrite and 1064 nm Nd:YAG laser energies at pulse durations ranging from 0.25 to 100 milliseconds. The device is used to treat various pigmentary disorders, provide skin rejuvenation treatments, treat vascular lesions and to provide effective, lasting hair removal treatments.
Pigmentary disorders are very effectively treated with the 755nm Alexandrite laser. With respect to pulse duration, millisecond pulses are used for the treatment of photo damage, freckles, seborrheic keratosis and lentigines while the treatment of Melasma or postinflammatory hyperpigmentation (PIH) requires shorter, microsecond level pulses as these lesions are very sensitive to thermal damage.
When treating melasma, one should not expect to see an immediate response, but rather a gradual improvement. In cases of immediate and fast response, the melasma will usually worsen within a few weeks post treatment. The ideal treatment course would involve frequent treatments providing slow, gradual results. Thus when treating melasma or PIH with the GentleLase Pro or GentleMax Pro’s 755nm Alexandrite handpiece, the treatment should include 2~3 passes using 8~10mm spot size with 1-3 Hz repetition, 0.25-0.35msec pulse duration and relatively low fluence of 6-7 J/cm2. Pulse stacking is usually not recommended. Multiple sessions are recommended once or twice per month.
When we treat pigmentary disorders in a practical situation, complex conditions are more common than simple cases. For example, melasma combined with Hori’s nevus, seborrheic keratosis and lentigines are more common than melasma alone. Occasionally the melasma is also combined with PIH caused by procedures the patient has had in the past. It is for these reasons that correct diagnosis and analysis of the lesion is crucial to treatment success. Closely matching the treatment spot size to the size of the lesion is also important when treating lentigines, seborrheic keratosis, or freckles. This is because the millisecond pulses used to treat them generate more heat than the shorter microsecond pulses and the risk of PIH always needs to be managed in the Asian skin type. Para or post-treatment cooling is necessary in the most cases when we use high fluence and millisecond pulse widths, but for microsecond pulse treatments epidermal protection and skin surface cooling may be optional.
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