Houston - The face of the aesthetic is changing, and cosmetic dermatologists must be able to offer these patients aesthetic options, said Brooks A. Jackson, M.D.

According to the 1990 census, 30 percent to 35 percent of the United States population is nonwhite. These groups are growing at rates of 2 to 18 times faster than the white population, and by the year 2056, more than half the U.S. population will be of non-European descent.

Dr. Jackson, a Mohs' fellow in Houston who completed a laser surgery fellowship at Harvard University, has concentrated recently on akin characteristics of African-Americans.

Skin Differences Studied

How do black skin and white skin differ?

Investigators sought to answer that question in a study of 38 women, 19 black and 19 white, who ranged in age from 22 to 50. Biopsies measuring 4mm from the women's malar cheeks showed that in black skin, the epidermal melanosomes are large, numerous, and spread uniformly throughout the entire epidermis.

In white skin, the melanosomes are small, sparse, clumped together in aggregates, and located primarily in the lower portion of the epidermis. Black skin shows little to no overt solar clastosis with aging, wheras white skin develops moderate to extensive clastosis.

These unique features of black skin protect it against actinic damage, Dr. Jackson said, making resurfacing for rhytides a nonissue.

Ethnic skin, however, has other challenges. Blacks are more susceptible to keloid development, and they have a higher incidence of pseudofolliculitis barbae.

The higher numbers of melanocytes in ethnic skin, plus their labile nature means that trauma - including that caused by dermatologic treatment - more easily causes pigmentation disturbances.

In spite of these concerns and in spite of black skin absorbing laser light differently from white skin, many lasers can effectively treat and improve the appearance of ethnic patients, she said.

Vascular, Pigmented Lesions

Treating black patients for vascular lesions is more difficult than treating white patients because black skin has more melanin, and melanin has a fairly wide absorption spectrum. Melanin competes for absorption with laser energy intended for the hemoglobin in the blood vessels. Nevertheless, lasers can be used to treat port-wine stains, telangiectases, verrucae, hypertrophic scars, atriae, and some keloids.

Lasers for vascular lesions can be divided into three groups: continuous-wave lasers, quasi-continuous wave and pulsed lasers. Some non-laser devices that emit intense, pulsed light are used for the treatment of vascular and pigmented lesions.

Lasers for pigmented lesions must generate a wavelength more highly absorbed by melanin than by hemoglobin or water. These are the green-light, continuous-wave lasers and the Q-switched lasers.

Benign, non-nevocellular lesions such as nervus of Ito and Ota do beautifully with pigmented lesion lasers, Dr. Jackson said. Melasma, cafe-au-lait spots, and post-inflammatory hyperpigmentation often return after initial improvement, so she tends not to treat those.

The debate continues over whether pigmented nevi should be treated with lasers. "I come down on the conservative side and do not," she said. Dr. Jackson believes these should be examined histologically rather than be vaporized in order to rule out atypia.

Tattoo Removal

Several factors influence how effective lasers are for eliminating tattoos. First is whether tattoos are applied professionally or by an amateur. In general, amateur tattoos resolve more quickly because they're usually made of blue or black ink or pencil lead. The pigment is seldom deep. Professional tattoos, on the other hand, are more complicated, consisting of several colors, and the pigment is placed deeper in the skin.

Laser choice is another factor. Blue or black tattoos respond well to the ruby laser, but in dark-skinned patients, the ruby leaves some hypopigmentation, Dr. Jackson said. Although it resolves in time, a better choice is the Nd:YAG 1064. Green pigment does best with the alexandrite, and red with the frequency doubled Nd:YAG 532.

"So unfortunately, in order to effectively remove tattoos, you need at least two lasers." she said.

Tattoo removal is not simply a cosmetic concern. "For many young people, the removal of a gang tattoo can mean the difference between life and death," she said. "Many communities have grass-roots organizations that will refer these patients to you and pay for the treatment if you will donate your time."

Although black patients do not have such an issue with photoaging, these patients request resurfacing for acne scarring and dermal lesions such as syringomas and dermatosis papulosa nigra. Many modalities of facial rejuvenation have been used. "As each has come to the market, it has undergone scrutiny and discussion and debate over whether or not it's been useful in the treatment of ethnic patients," Dr. Jackson said. For example, tretinoin (Retin-A), chemical peels, and dermabrasion can be effective without causing a significant amount of epidermic scarring.

So can lasers. The CO2 at 10,600nm, with an energy fluence greater than 5J (vaporization threshold), and at a pulse duration of less than 1ms, offers char-free ablation. The erbium YAG laser, with a fluence of 2,940nm, has a more shallow ablation depth, 5 to 30um, as opposed to 20 to 60um with the CO2 laser. This makes healing time shorter but causes less collagen and dermal contraction, so the results are not as dramatic. A newer resurfacing tool is the Nd:YAG with a cooling system, which results in new collagen synthesis in the papillary dermis without epidermal destruction.

Authors of a 1995 paper performed resurfacing on 30 Asian and Hispanic patients with skin types III and IV, for rhytides and acne scars. Patients were pretreated with hydroquinones and tretionin prior to CO2 laser resurfacing.

With the exception of some post-inflammatory hypopigmentation, all of the patients did well and none developed scarring. The authors concluded that resurfacing is safe in ethnic skin as long as patients adhere to pretreatment and post-treatment regimens regarding bleaching and sun avoidance.

How About Hair?

"hirsotism and hypertrichosis are extremely common in many ethnic groups," said Dr. Jackson. "One of the most exciting topics for me right now is the potential for the removal of hair in lesions of pseudofolliculitis barbae and acne keloid, both of which are caused by ingrown hairs."

Until recently, hair removal options included shaving, waxing, tweezing, chemical epilation, chemical depilatories and electrolysis. Now lasers and nonlaser light sources have been added to the armamentarium.

Because the target is the melanin within the hair shaft and the follicular epithelium, the laser's energy must be more readily absorbed by melanin than by hemaglobin or water. The following lasers meet that criterion:

• SoftLight Hair Removal Process (ThermoLase Corp.) uses a low-fluence, Q-switched Nd:YAG at 1,064 nm. It must be used in conjunction with a carbon-rich solution that enters the hair follicles and serves as a target chromophore.

• Two ruby lasers, used in normal (long-pulse) mode rather than the Q-switched mode used for tattoo removal are the EpiLaser (Palomar Medical) and the Chromos 694 (MEHL/Biophile International).

• Three long-pulse alexandrite lasers differ in pulse width: the EpiTouch (Sharplan) has a 2ms pulse width, the Gentlelase (Candela) has a 3ms pulse width, and the Photo-Genica LPIR (Cynosure) can be used at 5, 10, and 20ms.

• Another system being used for hair removal is the EpiLight (ESC) which is not a laser but a flash-lamp light source.

Curiosity is a Virtue

Dr. Jackson was curious about what would happen if lasers were used to remove hair in more melanized patients, and she also wanted to see the effects of different pulse widths.

For a pilot study, she selected eight patients - 4 women and 4 men - with skin types III through VI. She chose a Cynosure alexandrite laser at energy fluences of 14 to 20J, based on skin type. She treated each patient on two test areas (chosen from legs, beard, bikini and axillae) using a 20ms pulse width on one area and a 5ms pulse width on the other, at the same energy fluences. Punch biopsies of 3 and 4mm were taken from each site 10 minutes after treatment and read by an independent dermatopathologist who was blinded as to the protocol. Patients returned four weeks later for repeat biopsies and photographing.

The 5ms pulse width and the 20ms pulse width removed equal amounts of hair. Histologically, all of the patients showed some type of epidermal damage, more so from the 5ms pulse width than from the 20ms pulse width.

Scars formed in two patients using the 5ms pulse width. In hair shafts and epithelium, damage ranged from minimum to more significant, and was greater in the patients treated with the 5ms pulse. Those patients also demonstrated more clinical hypopigmentation. Therefore, it appears that the longer pulse duration is more appropriate for use in darker skin.