The Asian Dermatologic Patient: Review of Common Pigmentary Disorders and Cutaneous Diseases

Stephanie G.Y. Ho; Henry H.L. Chan

Disclosures

Am J Clin Dermatol. 2009;10(3):153-168. 

In This Article

4. Common Skin Diseases in Asians

A survey of 74 589 Asians over a 2-year period in Singapore[57] listed the most common diagnoses as atopic dermatitis, acne, and viral infections. The survey identified more cases of urticaria in the Chinese, more psoriasis and alopecia in Indians, and, unsurprisingly, more PIH in Malays and Indians, who tend to have darker skin compared with the Chinese.

4.1 Atopic Dermatitis

Atopic dermatitis (eczema) is a common presenting complaint in all dermatology clinics. There is some evidence suggesting that eczema is more common in the Chinese population. A survey of the 12-month cumulative incidence of atopic dermatitis in Chinese, Vietnamese, and White infants born in Melbourne, VIC, Australia showed that 44% of Chinese, 17% of Vietnamese, and 21% of White infants were affected.[58] A higher incidence of atopic dermatitis was also seen in Chinese infants compared with White infants living in San Francisco, CA, USA and Honolulu, HI, USA.[59]

However, a study conducted in Leicester, UK, found that although there were more referrals of atopic dermatitis to the dermatology department from the Asian community, the incidence was in fact the same in the Asian and non-Asian groups.[60] These investigators suggested a poor knowledge of atopic dermatitis amongst the Asian community as the reason for the higher rates of referral. Interestingly, there were frequent anecdotal reports from Asian patients of their disease resolving when they visited India or Africa and flaring up on their return to the UK, suggesting an environment-related influence on disease expression.

Management of atopic dermatitis is similar in the different ethnic groups, and includes emollients, topical corticosteroids, topical tacrolimus, phototherapy, oral antihistamines, and immunosuppressants in resistant cases.[61]

4.2 Acne

A population-based prevalence study of acne in Hong Kong adolescents reported 91.3% of their subjects to be affected.[62] The majority (52.6%) of the subjects developed scarring and pigmentation as a result of acne but only 2.4% had consulted a clinician. 26.6% were also disturbed psychologically by acne and 82.9% by its physical appearance. Topical medications were the mainstay of treatment. The study highlighted the importance of public education of the management of this exceedingly common condition, as well as early and aggressive intervention from clinicians, in order to prevent serious sequelae such as pigmentary changes, scarring, and psychological disturbances.

The acne hyperpigmented macule is common in skin of color and persists for an average of 4 months or longer.[63] Ice-pick scarring or keloidal scarring may also occur and can have a significant impact on the self-esteem of affected individuals.

Treatment modalities for acne include topical antibacterials, retinoids, adapalene, azelaic acid, oral antibacterials, hormonal treatments, and oral isotretinoin. Tetracyclines are effective against acne but can be phototoxic. Strict sun avoidance and protection are therefore essential when using tetracyclines, especially in skin of color. Macrolides such as erythromycin and clarithromycin are non-phototoxic and should be considered as first-line antibacterial treatment in Asians.[62] Bleaching agents such as hydroquinone may be used alone or in combination with other retinoids and corticosteroids for treatment of the acne hyperpigmented macule.[63]

Ablative laser resurfacing using carbon dioxide and erbi-um:YAG lasers has been shown to be effective in the treatment of atrophic acne scars.[64,65,66] Clinical improvements of 30-75% can be achieved for patients with superficial atrophic acne scars. However, this approach is associated with significant downtime and adverse effects, which include erythema, hyperpigmentation, and hypopigmentation, that may be permanent.

Different wavelengths within visible radiation have been used to treat acne. Blue light causes activation of endogenous porphyrins in Proprionibacterium acnes and kills the bacteria.[67] However, in Asian patients, an increase in pigmentation can occur after prolonged blue light exposure and this is therefore not an ideal treatment modality in skin of color.[14] PDL targeting hemoglobin has been suggested to be effective in the treatment of inflammatory acne with few adverse effects.[68] However, inconsistent findings have been reported and further confirmatory studies are required.[69] Photodynamic therapy, using a variety of visible wavelengths and a number of photosensitizing dyes, has been used to treat acne.[70,71] A previous study showed a statistically significant clearance of inflammatory acne by topical aminolevulinic acid (3-hour occlusion) and red light for at least 20 weeks after four treatments, and for 10 weeks after a single treatment.[72] Significant adverse effects such as transient hyperpigmentation, exfoliation, and crusting were observed. In Asians, short-contact aminolevulinic acid (10-hour occlusion) followed by activation using an IPL source can be effective against acne, with erythema being the main complication.[14]

Infra-red lasers are increasingly being used in the treatment of acne and acne scarring. Use of a non-ablative 1450-nm diode laser with cryogen cooling spray for the treatment of atrophic acne scars in 57 Asian patients was evaluated by Chua et al.[73] These investigators reported mild improvement of 16-20% after four to six treatments. Conventional single-pass, high-energy (11-12 J/cm2) treatment was used in this study. Pain, erythema, and marked PIH in 39% of treated patients were reported. Bernstein[74] recently published a pilot study demonstrating superiority of low-fluence (8-11 J/cm2), double-pass 1450-nm diode laser treatment over conventional treatment. Low-fluence, double-pass therapy reduced acne counts and pain to the extent that a topical anesthetic could be omitted. Recently, we evaluated use of a low-fluence, multiple-pass approach in the treatment of acne vulgaris among Chinese patients and found that it was effective in those with inflammatory acne, with a low prevalence of PIH (figure 4).

Figure 4.

Treatment of inflammatory acne with a 1450-nm diode laser: (a) pre-treatment; (b) post-treatment.

Fractional photothermolysis is particularly effective in the treatment of acne scarring in skin of color, and indeed this is one of the main indications for its use. However, PIH is a potential complication of this approach. In a recent retrospective study of 37 Chinese patients who underwent fractional resurfacing for acne scarring and skin rejuvenation, Chan et al.[13] concluded that while both energy and density parameters are important considerations for reducing PIH in Asians, density is of particular importance. These investigators concluded that in order to prevent PIH, a high-energy and low-density treatment is preferable. A recent study in Asian patients by Kono et al.[75] reported similar findings and demonstrated that patient satisfaction was also increased when higher fluence rather than higher density was used. The importance of adjunctive cooling and lengthening of the treatment interval to 2-4 weeks for epidermal lesions and 4-6 weeks for dermal lesions to reduce the risk of PIH has also been emphasized.[13]

4.3 Hypertrophic and Keloid Scarring

It is well known that hypertrophic and keloid scars are more common in individuals of Asian descent than in their Caucasian counterparts.[76] Both types of scars are characterized by deposition of collagen and glycoprotein. However, they differ clinically; keloids extend beyond the original wound whilst hypertrophic scars remain within the borders of the original wound.

Silicone gels are commonly used with some success for the treatment of keloids and hypertrophic scars. However, a successful outcome is highly dependent on patients adhering to the treatment regimen over a long period of time.[76] The efficacy of corticosteroid injections in the treatment of keloids and hypertrophic scars is well established. Corticosteroids have anti-inflammatory and vasoconstrictive effects, together with an anti-mitotic effect on fibroblasts and keratinocytes.[77] The most commonly used corticosteroid is triamcinolone. This agent is normally administered intralesionally into the scar, at a concentration of 10-40 mg/mL, every 4-6 weeks for several months or until the scar is flattened. Multiple adverse effects, including atrophy, telangiectasia, and pigmentary changes, can occur.[78,79] Recently, combined use of intralesional triamcinolone and fluorouracil in the treatment of inflamed hypertrophic scars has been reported to be effective and can avoid these potential complications.[80]

The 585-nm PDL appears to be effective in the treatment of keloid and hypertrophic scars. Vascular proliferation plays a key role in the early phase of scar formation. Through selective photothermolysis, the light energy emitted from a PDL is absorbed by hemoglobin, generating heat and leading to coagulation necrosis.[81,82] Clinical studies of PDL treatment of scars have noted no significant difference in treatment outcomes when minor variations in fluence were used.[83] However, there was a trend for lower fluences to be associated with greater improvement. Manuskiatti and Fitzpatrick[84] evaluated the clinical response of keloidal and hypertrophic scars after treatment with an intralesional corticosteroid alone or combined with fluorouracil, fluorouracil alone, and the 585-nm flashlamp-pumped PDL. They found a significant clinical improvement in all treated segments, but no significant difference between the different treatment modalities. Intralesional formulas resulted in faster resolution of scar compared with PDL. Scar texture (erythema and pliability) responded better to PDL. Another study that evaluated use of PDL in 29 Chinese patients with hypertrophic scars showed that apart from an improvement in pruritus, there was no significant difference in scar thickness between the treatment and control groups.[85] However, a supra-purpuric dose was used and excessive injury may have led to the poorer observed clinical outcome. Post-operative purpura persisting for 7-10 days has also been reported following PDL use in other studies.[86] These findings suggest that early treatment with a combination of intralesional triamcinolone and fluorouracil to flatten the scar, followed by sub-purpuric PDL to improve color, texture, and pruritus, may be the most effective approach.

4.4 Psoriasis

Psoriasis was the seventh most common skin condition in a large Asian patient survey conducted in Singapore.[57] However, psoriasis is more commonly seen in Caucasians than in Asians and Africans, and is very rare in Native Americans and Hispanics.[87] Treatments for psoriasis include topical corticosteroids, tar, calcipotriene (calcipotriol), UVB, psoralen plus UVA (PUVA), and other oral immunosuppressants such as methotrexate, acitretin, and cyclosporine (ciclosporin). An interesting study examining 4294 long-term PUVA patients in Japan, Korea, Thailand, Egypt, and Tunisia found no apparent increased risk of non-melanoma skin cancer with long-term PUVA therapy in Asian patients.[88] This is in contrast to the Caucasian experience, for which strict PUVA therapy guidelines exist because of the increased risk of cutaneous malignancies. Phototherapy is therefore a useful long-term treatment option for Asians with psoriasis and other skin conditions such as vitiligo, cutaneous T-cell lymphoma, and atopic dermatitis.

4.5 Primary Cutaneous Amyloidosis

Primary cutaneous amyloidosis presents most commonly as either lichen or macular amyloidosis. It is a condition commonly seen in southeast Asia and some South American countries.[89] Lichen amyloidosis is a persistent, pruritic, popular, and plaque-like eruption with a predilection for the shins and extensor arms, and is most commonly seen amongst the Chinese. Macular amyloidosis presents as small brown macules coalescing into patches distributed typically in a rippled, symmetric pattern on the upper back, limbs, chest, and buttocks. It most commonly presents together with lichen amyloidoisis as biphasic amyloidosis. Histologically, deposits of amyloid are seen in the papillary dermis, and the diagnosis can easily be confirmed by staining the amyloid red using congo red or metachromatically using crystal violet or toluidine blue.[90,91]

Anosacral amyloidosis is a rare form of cutaneous amyloidosis reported previously in Chinese and Japanese patients only.[92] It presents as pruritic, well demarcated, brownish patches or plaques fanning out in lines from the anus to the sacral region. It is more common in men. This condition can be easily mistaken as lichen simplex chronicus, PIH, and tinea cruris and a skin biopsy should be carried out if the diagnosis is in doubt.

Treatment of cutaneous amyloidosis can be difficult. Reducing friction to the skin is important. Topical high-potency corticosteroids, oral retinoids, and cyclophosphamide have also been reported to be beneficial.[93]

4.6 Kawasaki Disease

Kawasaki disease is an acute febrile vasculitis that may lead to coronary artery abnormalities. It has a much higher incidence in Asian children.[94,95] The diagnostic criteria include fever (>38.3°C) of 5 days duration plus at least four of the following five criteria: (i) peripheral extremity changes; (ii) polymorphous exanthem; (iii) non-purulent bilateral conjunctival injection; (iv) changes in the lips and oral cavity, such as erythema and strawberry tongue; and (v) acute, non-purulent cervical adenopathy.[96] The polymorphic cutaneous eruption lasts 10-20 days and then subsides. One to two percent of patients may die of a myocardial infarction soon after apparent recovery from the acute illness.[91]

Diagnosis of Kawasaki disease is very important because steps to prevent coronary aneurysm and myocardial infarction can then be taken. All patients should be hospitalized during the acute febrile stage, and a baseline echocardiogram performed.[91] A single dose of intravenous γ-globulin at 2 g/kg should be given over a 10- to 12-hour infusion. Aspirin (acetylsalicylic acid) should also be started at 100 mg/kg/day until the fever is controlled or until day 14 of the illness, followed by 5-10 mg/kg/day until the sedimentation rate and platelet count are normal. The patient should have a repeat echocardiogram 3-4 weeks after onset of fever. If both echocardiograms are normal, no further imaging needs to be done. Patients should, however, be followed up periodically. The disease is self-limiting and the prognosis for most children is good if an early diagnosis is made.[91] Studies have shown that a delay in diagnosis of >10 days or occurrence in infants aged <1 year carries a significantly higher risk of coronary artery abnormalities.[94]

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