Chapter 48: Management of Dyschromias

INTRODUCTION

Dyschromia is a broad term used for disorders of pigmentation. Three common pigmentary issues are melasma, postinflammatory hyperpigmentation (PIH), and dermatoheliosis. All are characterized by increased melanin deposition in the skin, although the pathogenesis of each increase is distinct.

The treatment of dyschromia is accomplished with topical therapies, chemical peels, and lasers. Dermatoheliosis is the most easily treatable of the forms of dyschromia. Melasma and PIH are far more challenging. This chapter will review the treatment options for each of these disorders.

MELASMA

Melasma is hyperpigmentation of the face, usually seen in women with Fitzpatrick skin types III to IV and typically distributed on the central face, malar, or mandibular areas. This chronic disorder occurs in 50% of pregnant women and 10% of men.¹ The prevalence has been reported to be 40% in Southeast Asia and to range from as low as 8% to as high as 80% among Latina females.^2,3

Melasma is caused by increased melanin pigment deposition in the skin triggered by ultraviolet light, visible light, and hormones such as in pregnancy, oral contraception, and hormone replacement therapy.^1,4 Thyroid disorders, genetic predisposition, and antiseizure and phototoxic medications are other risk factors that may affect melasma.¹ Epidermal barrier dysfunction may also play a role.⁵

The pigmentation in melasma is due to enlarged melanocytes, increased melanosomes, increased melanin content in keratinocytes, and melanin deposition in melanophages.^5,6 Traditionally, melasma has been classified as epidermal, dermal, or mixed type^2,7; however, confocal microscopy has demonstrated that most melasma is mixed, with epidermal hyperpigmentation playing the primary role.^5,8 Dermal pigmentation contributes less to the clinical manifestations; however the dermal fibroblasts may be involved in signaling pathways that lead to melasma.⁵ Wood’s light examination, historically used to distinguish epidermal and dermal melasma, has not been found to be clinically accurate.^6,9,10

Therapies for melasma include topical lightening creams, chemical peels, and lasers. Even oral treatments have been tried, although the utility of this approach needs to be further elucidated.¹¹ Treatment can be challenging and is often characterized by recurrence. Long-term remission can be difficult to achieve.

TOPICAL TREATMENTS

Lightening agents. Hydroquinone (1,4 dihydroxybenzene) is the most commonly used lightening agent for melasma. It inhibits the enzyme tyrosinase and prevents the conversion of l-3,4 dihydroxyphenylalanine to melanin, leading to altered melanosome production and increased melanosome destruction.^1,12 In combination with sun protection, this medication can improve the epidermal component of melasma. Hydroquinone 4% may be used twice a day on a regular basis for short periods of time. The recommended treatment time varies and ranges from 8 weeks to 6 months, depending on the hydroquinone formulation.¹³

Although generally well tolerated, hydroquinone can be associated with adverse effects. It can cause redness and irritation, ...