INTRODUCTION
The evolving demographic landscape of the United States necessitates that dermatologists become knowledgeable
of the various nuances implicit in pigmented skins when choosing a dermatologic medication. Topical retinoids
have been an important class of drugs since their inception
nearly three decades ago. With varied success, they have been used to treat numerous dermatoses including acne vulgaris, psoriasis, photoaging, Kaposi sarcoma, cutaneous T-cell lymphoma and disorders of hyperkeratosis.1 Retinoid responsive
conditions more common in pigmented skins include melasma, post-inflammatory hyperpigmentation, keloids and pseudofolliculitis barbae.
Retinoids exhibit their biological effects via activation of two different families of nuclear retinoid receptors termed the retinoic
acid receptors and the retinoid X receptors.2 Each retinoic acid receptor comprises three different receptor subtypes (alpha,
beta and gamma) which are encoded by distinct genes.3 Once bound to the nuclear receptor, the drug-nuclear receptor complex binds to retinoic acid response elements, which are enhancing elements responsible for gene transcription.3 The pharmacologic effect of each retinoid is mediated in part by the specific subset of receptors to which it binds.
According to data from the U.S Census Bureau, the non-Hispanic
white population will decrease from 69 percent in 2000 to 50 percent by the year 2050. Simultaneously, rapid growth is expected to continue in the Asian/Pacific Islander and Latino segments.4 These numbers illustrate a dramatic shift in patient demographics that will occur in years to come. The intent of this article is to review the use of topical retinoids in pigmented skins and develop a set of general guidelines based on the literature
and our personal experience.
Clinical Indications
Post-Inflammatory Hyperpigmentation (PIH)
The two most common dermatologic diagnoses among black patients have been reported to be acne and dyschromias.5,6 Likewise, dyschromias rank as the fourth most common diagnosis
in Hispanics.7 Retinoids are useful in the treatment of hyperpigmentation because they reduce epidermal melanin by blocking the transcription of tyrosinase, induce desquamation, disperse keratinocyte pigment granules and enhance epidermal
cell turnover via epidermopoiesis.7,8
The efficacy of hydroquinone, the gold standard treatment for hyperpigmentation, is improved by adding a topical retinoid. When used in conjunction with a topical steroid and hydroquinone,
tretinoin has been shown to contribute to epidermal absorption of hydroquinone and prevents corticosteroid-induced
epidermal atrophy.9
Post-inflammatory hyperpigmentation is an acquired disorder characterized by excess deposition of melanin in the epidermis, dermis, or both occurring secondary to cutaneous inflammation
or injury. Although the exact mechanism of PIH remains unclear, it is postulated that inflammatory cells release cytokines
and other mediators which are capable of stimulating melanocytes and increasing melanin synthesis.10
There have been several trials that have investigated the use of topical retinoids in the treatment of PIH in pigmented skins. One such trial involving 54 black subjects with PIH compared the efficacy of tretinoin 0.1% cream applied daily to a vehicle control. After 40 weeks, colorimetry determined a 40 percent lightening of lesions occurring in the tretinoin group versus 18 percent lightening with vehicle. In addition, there was a 23
