Melasma

Melasma occurs in sun-exposed areas as an acquired hypermelanosis, presenting as symmetrically distributed hyperpigmented macules which can be confluent or punctate. It is worse in areas that receive excessive sun exposure, including the cheeks, the upper lip, the chin, and the forehead.

No laboratory tests are indicated although some studies suggest mild abnormalities in thyroid function are associated, specifically pregnancy- or oral contraceptive pill-associated melasma. In these cases, it is reasonable to consider checking thyroid function tests. Wood lamp examination helps to localize the pigment to the dermis or epidermis.[8][9][10]

The best treatment is a topical combination of hydroquinone cream and avoidance of sun or estrogen exposure. In addition to the avoidance of sun exposure, discontinuing the use of high-SPF sunscreens (50 or higher) can prevent the development of melasma. First-line therapy for melasma consists of effective topical therapies, mainly in the form of triple combinations (hydroquinone 4%, tretinoin 0.05%, and fluocinolone acetonide 0.01%) and when triple combinations are unavailable or when patients have hypersensitivity to them, then dual ingredients or single agents be considered.

Chemical peels and lasers may yield unpredictable results and are associated with adverse effects including epidermal necrosis, postinflammatory hyperpigmentation, and hypertrophic scars. These interventions are second-line therapies and used only if the topical medication has failed. In experienced hands, chemical peels and lasers are usually safe and may produce results faster than topical medications.

Skin Peels These procedures carry a risk of adverse outcomes. Peels use glycolic or salicylic acid-based compounds which may increase turnover of hyperpigmented keratinocytes. 

• They often begin as a monthly treatment using low concentration formulas and progress to weekly applications at higher concentrations. 
• Lightening agents are usually used in conjunction with superficial peels for better results. 
• Skin peels should only be used after a trial of therapy with at least one skin-lightening agent. 
• Close monitoring of skin depigmentation is necessary, and therapy should be halted if alterations in pigmentation in the surrounding skin are noted.

Lasers

The efficacy of lasers for the treatment of melasma has been associated with undesired cosmetic results. Their use should be considered in cases of extensive disease that is refractory to laser use as it may actually worsen the condition.

The differential diagnoses include:

• Actinic Lichen Planus
• Acanthosis Nigricans
• Discoid Lupus Erythematosus
• Drug-Induced Photosensitivity
• Exogenous Ochronosis
• Frictional Melanosis
• Mastocytosis
• Nevi of ito and Ota
• Pigmented Contact Dermatitis
• Poikiloderma of Civatte
• Postinflammatory Hyperpigmentation

Melasma has no associated mortality or morbidity. No cases of malignant transformation or association with the increased risk of melanoma or other malignancies have been reported. Patients with melasma actually are considered to have less risk for melanoma. 

The dermal pigment may take longer to resolve than the epidermal pigment because no effective therapy is capable of removing dermal pigment. However, treatment should not be withheld simply because of a preponderance of dermal pigment. The source of the dermal pigment is the epidermis, and, if epidermal melanogenesis can be inhibited for long periods, the dermal pigment will not replenish and will slowly resolve.

Resistant cases or recurrences of melasma occur often and are certain if strict avoidance of sunlight is not rigidly heeded.

Patients should avoid the routine use of cosmetics on sensitive skin. Vigorously rubbing triple creams on hyperpigmented areas may worsen the situation. Ochronosis can occur with prolonged exposure to creams with potent steroids.

Melasma should be distinguished from post-inflammatory hyperpigmentation, actinic lichen planus, and hydroquinone-induced exogenous ochronosis.

Patient education should include strict sun avoidance as this is essential for resolution and may prevent recurrence of melasma. Melasma patients should apply bleaching creams to dark areas only. Resolution with strict sun avoidance and topical bleaching creams can take many months; patients should be educated to expect slow but gradual lightening.

Melasma is a benign skin disorder that has no morbidity. The key reason why some patients seek treatment is aesthetic. Fortunately, melasma resolves on its own in most cases. Thus, healthcare workers including nurse practitioners, dermatologists, and primary care providers should educate the patient on avoiding the sun and discontinuing the trigger medications. There are dozens of treatments for melasma and none is superior to the other. In fact, some treatments like the laser may worsen the condition.

Patients who seek no treatment and avoid the sun will notice that the rash usually disappears in a few months.[11]