More people from varied ethnic backgrounds are now presenting to the dermatologist. Although acne is ranked as the number 1 or 2 dermatologic disease among blacks, Hispanics, and Asians, it is less common in these groups than it is in whites. People with dark skin tend to have less severe acne.
The Differences in Skin Structure
o In black patients,
the stratum corneum is compact and has multiple layers.
o The stratum corneum of Hispanics and Asians is similar to that of whites.
o Sebaceous glands tend to be larger and more active in black patients.
o The follicular epithelium of the pilosebaceous gland is thicker in black patients.
o Blacks tend to have more multinucleated giant cells in their skin, and they are more reactive in the acne state.
o Lesions in black skin that appear to be non-inflammatory clinically often have evidence of inflammation when biopsied.
o This underlying inflammation is responsible for the development of hyperpigmented macules that sometimes occur in patients with dark skin.
o Black patients with acne tend to have an abundance of inflammatory cells, even if their only clinical sign of disease is open, "noninflammatory" comedones.
o Scant or no research has been done on inflammation in Asian or Hispanic acne skin.
Targeting Acne Pathogenesis
o Hyperkeratinization defects within the follicle can be treated with topical retinoids, regardless of ethnic skin type.
o Darker skin types tend to be irritated easily by the early formulations of topical tretinoin and are better served by the newer, less irritating topical retinoids.
o White patients and light-skinned patients, such as those of Chinese or Japanese heritage, will benefit from adapalene (Differin®), which is a naphthoic acid in a creamy gel.
o Dr Halder's first choice of combination therapy for ethnic skin is a topical retinoid plus a topical antibiotic. He will sometime use benzoyl peroxide plus a topical antibiotic for mild acne, if the patient is light-skinned.
Severity of Acne
o Whites are most susceptible to nodulocystic and fulminant acne.
o Hispanic patients have a frequency of nodulocystic acne that is higher than that in blacks or Asians, but not as high as that in white patients.
o Corticosteroid injections of no more than 5 mg/mL can be used to resolve inflamed papular or pustular lesions or cysts in dark skin.
o Oral isotretinoin (Accutane) should be reserved for patients who have nodulocystic acne or those whose acne has not responded to other therapy after a prolonged period of time.
o Acne surgery may cause postinflammatory hyperpigmentation in dark skin. When it is necessary, however, a topical retinoid should be used for 6 weeks before the procedure to loosen follicular plugging.
Postinflammatory Hyperpigmentation
o Dark-skinned patients are often more concerned about postinflammatory hyperpigmentation than they are about acute inflammatory lesions.
o Distress over postinflammatory hyperpigmentation can lead to depression and social withdrawal, particularly in adolescents.
o The inflammatory response in acne causes degeneration of the melanocytes in the basal cell layer of people with dark skin. The melanin from those melanocytes condenses, resulting
in hyperpigmentation.
Pseudofolliculitis barbae
o Pseudofolliculitis barbae affects approximately 45% to 80% of black men.
o It can also affect men of other ethnicities, including white men and those of Mediterranean descent.
o Pseudofolliculitis barbae arises from 1 of 2 mechanisms: (1)
extrafollicular penetration, which is a foreign-body reaction to a hair that coils back into the follicle; and (2) transfollicular penetration, in which the hair is trapped under the epidermis because the skin was stretched during shaving.
o Lesions caused by transfollicular penetration resemble papulopustules.
o Pseudofolliculitis barbae can be treated with topical retinoids at night combined with topical steroids during the daytime.
o A combination of benzoyl peroxide with a topical antibiotic may be useful in some cases.
Future Research
o More basic science studies need to be done to delineate the differences between ethnic skin types.
o We do not yet know if sebum composition varies across ethnicities.
o We need to know more about immunoreactivity, response to allergens, and response to cosmetics.
