Ann Thorac Surg. 2002 Jan;73(1):314-5.
Pneumomediastinum during spontaneous vaginal delivery.
Sutherland FW1,
Ho SY,
Campanella C.
We report two rare cases of spontaneous pneumomediastinum that presented shortly after childbirth and resolved without treatment.
Spontaneous pneumomediastinum has been described in a wide range of seemingly unrelated but recurrent clinical scenarios.
We highlight their common etiologic factors and provide the anatomic and physiologic bases for the radiologic signs that are common in all these conditions.
Clin Exp Dermatol. 2005 Sep;30(5):515-8.
A case of multicentric reticulohistiocytosis with multiple lytic skull lesions.
Ho SG1,
Yu RC.
Multicentric reticulohistiocytosis (MR) is a rare multisystemic disorder of unknown aetiology characterized by cutaneous and joint manifestations.
It is associated with malignancy in up to 31% of cases. Common radiological findings are peri-articular erosions and osteolytic punched-out areas.
We present a case of MR with cutaneous nodules, joint pains, and multiple lytic skull lesions--a combination that has not been described before.
Osteolytic activity of proinflammatory cytokines (tumour necrosis factor-alpha and interleukin-1) may explain the peri-articular erosions often seen in MR, and the multiple lytic skull lesions seen in our patient.
British Journal of Dermatology. 2005 Aug;153(2):364-367.
Analysis of para-phenylenediamine allergic patients in relation to strength of patch test reaction.
Ho SG1,
Basketter DA,
Jefferies D,
Rycroft RJ,
White IR,
McFadden JP.
BACKGROUND:
Despite having a positive patch test reaction to para-phenylenediamine (PPD), some patients continue to dye their hair, while others are forced to give up or abandon this practice.
This difference in patient behaviour could be due to the degree of sensitization.
OBJECTIVES:
To establish whether the ability to continue dyeing hair in PPD allergic patients is related to the strength of patch test reaction.
To note differences in other clinical features in relation to the strength of patch test reaction.
METHODS:
We analysed retrospectively the patch test records of 400 sequential PPD-positive patients for the strength of patch test reaction (+, ++, +++) and different clinical features.
Data were analysed using Cochran-Mantel-Haenszel chi2 tests.
RESULTS:
There was a strong linear relationship between the strength of patch test reaction and continuation with hair dyeing.
Patients were more likely to report a history of hair dye reaction with increasing strength of patch test reaction.
There was no difference in strength of patch test reaction in relation to age, site of rash, occupation (hairdressing) or history of atopic eczema.
Overall concomitant reactivity with related aromatic amine allergens (benzocaine, N-isopropyl-N-phenyl-para-phenylenediamine, para-aminobenzoic acid) was infrequent.
CONCLUSIONS:
Patients with stronger patch test reactions (++, +++) are more likely to have a clear history of reacting to hair dye and are less likely to still be dyeing their hair.
Contact Dermatitis. 2007 Jan;56(1):35-7.
Patch test frequency to p-phenylenediamine: follow up over the last 6 years.
Patel S1,
Basketter DA,
Jefferies D,
White IR,
Rycroft RJ,
McFadden JP,
Ho SY.
While the frequency of patch test reactivity to many cosmetic allergens has decreased over the last 20 years,
we have previously shown that in our clinic, the patch test reactivity to p-phenylenediamine (PPD) has remained stubbornly high between 2.5% and 4.2% in the years when patch testing was performed with 1% PPD.
Further retrospective analysis of the PPD patch test frequency over the last 6 years shows an increasing rate of PPD patch test frequency, showing an upward linear trend.
This increasing trend cannot be fully explained by any increase in patch testing of Southern Asian patients or of sensitization caused by PPD exposure from 'temporary henna tattoos'.
An alternative explanation may be the increasing use of permanent hair dyes.
Am J Clin Dermatol. 2009;10(3):153-68.
The Asian dermatologic patient: review of common pigmentary disorders and cutaneous diseases.
Ho SG1,
Chan HH.
The Asian patient with Fitzpatrick skin types III-V is rarely highlighted in publications on cutaneous disorders or cutaneous laser surgery.
However, with changing demographics, Asians will become an increasingly important group in this context.
Although high melanin content confers better photoprotection, photodamage in the form of pigmentary disorders is common.
Melasma, freckles, and lentigines are the epidermal disorders commonly seen, whilst nevus of Ota and acquired bilateral nevus of Ota-like macules are common dermal pigmentary disorders.
Post-inflammatory hyperpigmentation (PIH) occurring after cutaneous injury remains a hallmark of skin of color.
With increasing use of lasers and light sources in Asians, prevention and management of PIH is of great research interest.
Bleaching agents, chemical peels, intense pulsed light (IPL) treatments, and fractional skin resurfacing have all been used with some success for the management of melasma.
Q-switched (QS) lasers are effective for the management of epidermal pigmentation but are associated with a high risk of PIH.
Long-pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers and IPL sources pose less of a PIH risk but require a greater number of treatment sessions.
Dermal pigmentary disorders are better targeted by QS ruby, QS alexandrite, and QS 1064-nm Nd:YAG lasers, but hyper- and hypopigmentation may occur.
Non-ablative skin rejuvenation using a combination approach with different lasers and light sources in conjunction with cooling devices allows different skin chromophores to be targeted and optimal results to be achieved, even in skin of color.
Deep-tissue heating using radiofrequency and infra-red light sources affects the deep dermis and achieves enhanced skin tightening, resulting in eyebrow elevation, rhytide reduction, and contouring of the lower face and jawline.
For management of severe degrees of photoaging, fractional resurfacing is useful for wrinkle and pigment reduction, as well as acne scarring.
Acne, which is common in Asians, can be treated with topical and oral antibacterials, hormonal treatments, and isotretinoin.
Infra-red diode lasers used with a low-fluence, multiple-pass approach have also been shown to be effective with few complications.
Fractional skin resurfacing is very useful for improving the appearance of acne scarring.
Hypertrophic and keloid scarring, another common condition seen in Asians, can be treated with the combined used of intralesional triamcinolone and fluorouracil, followed by pulsed-dye laser.
Esthetic enhancement procedures such as botulinum toxin type A and fillers are becoming increasingly popular.
These are effective for rhytide improvement and facial or body contouring.
We highlight the differences between Asian skin and other skin types and review conditions common in skin of color together with treatment strategies.
Clin Exp Dermatol. 2010 Oct;35(7):717-22.
Methotrexate versus traditional Chinese medicine in psoriasis: a randomized, placebo-controlled trial to determine efficacy, safety and quality of life.
Ho SG1,
Yeung CK,
Chan HH.
BACKGROUND:
Psoriasis is a common and chronic immune-mediated skin disorder, for which there is currently no cure. To our knowledge, this is the first randomized placebo-controlled trial comparing methotrexate and traditional Chinese medicine (TCM) in terms of efficacy, safety, and quality of life for the treatment of psoriasis.
METHODS:
In total, 61 patients with moderate to severe plaque psoriasis were randomized to receive treatment with methotrexate, TCM or placebo for 6 months.
The primary outcome measure was the Psoriasis Area and Severity Index (PASI), and secondary outcome measures were the Physician's Global Assessment (PGA) and the Psoriasis Disability Index (PDI).
RESULTS:
In all, 50 patients completed the study and were included in the analysis.
Dropout rates were highest in the TCM group. Mean PASI change from baseline at 6 months revealed an improvement of 73.9% of the methotrexate group, 15.1% of the TCM group and 32.0% of the placebo group.
There was a significant difference between the three groups, with methotrexate showing greater effectiveness than the other two groups.
No significant difference was found between the TCM and placebo groups. The methotrexate group also had greater improvement when assessed using the PGA and PDI.
CONCLUSIONS:
Our results verify the therapeutic effect of methotrexate for the management of psoriasis. Despite widespread belief and use of TCM in Asia for the treatment of psoriasis, we were unable to confirm the efficacy of TCM in this study.
Lasers Surg Med. 2010 Oct;42(8):712-9.
A case series of facial depigmentation associated with low fluence Q-switched 1,064 nm Nd:YAG laser for skin rejuvenation and melasma.
Chan NP1,
Ho SG,
Shek SY,
Yeung CK,
Chan HH.
BACKGROUND AND OBJECTIVE:
In recent years, "laser toning" using low fluence, large spot size, multiple passed Q-switched 1,064 nm Nd:YAG laser has gained much popularity in Asian countries for non-ablative skin rejuvenation and the treatment of melasma.
This case series highlights one of the complications associated with laser toning, which is facial depigmentation.
MATERIALS AND METHODS:
Fourteen patients with laser toning-associated facial depigmentation were assessed with cross-polarized and ultraviolet (UV) photographic images.
The laser toning regimens received by these patients, as well as the treatment given for depigmentation, were analyzed retrospectively.
RESULTS:
All 14 patients were Chinese females, 9 of whom received laser toning for non-ablative skin rejuvenation and the other 5 for melasma. The treatment regimens received by these patients were highly variable.
The total number of treatments received ranged from 6 to 50 (mean 22.07). In all cases, UV photographic images demonstrated facial mottled depigmentation. Laser toning failed to significantly improve melasma in all five patients.
Five patients received targeted narrowband UVB for depigmentation with good clinical results.
CONCLUSIONS:
Laser toning with low fluence Q-switched 1,064 nm Nd:YAG laser for skin rejuvenation and melasma can be associated with mottled depigmentation.
With laser toning being frequently performed, this complication may become more commonly encountered in clinical practice.
The depigmentation can appear after only a few treatment sessions, and can cause much disfigurement, especially in cases with background melasma.
Further studies on laser toning are needed with the view to optimizing efficacy and minimizing side-effects.
Lasers Surg Med. 2010 Nov;42(9):615-23.
Fractional ablative carbon dioxide laser resurfacing for skin rejuvenation and acne scars in Asians.
Chan NP1,
Ho SG,
Yeung CK,
Shek SY,
Chan HH.
BACKGROUND AND OBJECTIVES:
Ablative fractional resurfacing (AFR) is a new modality for photorejuvenation and acne scars which combines carbon dioxide (CO2) laser ablation with fractional photothermolysis. The objective is to evaluate the efficacy and side effects of a new fractional CO2 ablative device (Fraxel Re:pair) for skin rejuvenation and acne scars in Asians.
MATERIALS AND METHODS:
Nine patients underwent one full-face treatment. The energy levels ranged from 30-70 mJ with coverage between 30% and 45%. Improvement in skin texture, laxity, wrinkles, enlarged pores, overall pigmentation irregularity, and adverse effects were assessed up to 6 months post-treatment. Standardized photographs using the Canfield Visia CR system
® were assessed by two independent observers. Subjective improvement was assessed by patient questionnaires.
RESULTS:
Nine Chinese patients (skin types III and IV, mean age 44.8) were included. Statistically significant improvements were seen for skin texture, skin laxity, wrinkles, enlarged pores, and acne scars. The post-inflammatory hyperpigmentation rate was 55.5% and 11.1% at 1 and 6 months post-treatment, respectively. Eighty-six percent of patients were overall satisfied to very satisfied with the treatment.
CONCLUSION:
Ablative fractional CO2 laser resurfacing was overall safe and effective for skin rejuvenation and acne scars in Asians. However, in view of the high post-inflammatory rate and the statistically significant but only mild to moderate improvement after a single treatment as observed in this study, there is a need to review the current role of fractional ablative CO2 laser treatment as compared to fractional non-ablative for skin rejuvenation and acne scar treatment in Asians.
Lasers Surg Med. 2010 Dec;42(10):710-5.
The use of non-ablative fractional resurfacing in Asian acne scar patients.
Chan NP1,
Ho SG,
Yeung CK,
Shek SY,
Chan HH.
BACKGROUND AND OBJECTIVES:
Non-ablative fractional resurfacing (NA FR) has been shown to be effective for photorejuvenation and acne scarring. Previous studies indicated that density, more than pulse energy, was associated with post-inflammatory hyperpigmentation (PIH) in Asians. The objective of this retrospective study was to assess the efficacy and complications of eight passes of NA FR ('full-NA FR') with the 1,550 nm erbium-doped fibre fractional laser (Fraxel SR laser system, Solta Medical, Hayward, CA) versus four passes ('mini-NA FR') with comparable pulse energy and treatment level as 'full-NA FR', but double the number of treatment sessions in Asian acne scar patients.
MATERIALS AND METHODS:
Forty-seven Asian atrophic facial acne scar patients who received full-face full-NA FR or mini-NA FR treatments between December 2005 and February 2009 were included. All photographic images captured with the Canfield Visia CR system at baseline and follow-ups were assessed for clinical efficacy and complications by an independent, non-treating and blinded physician.
RESULTS:
The total treatment densities for full-NA FR and mini-NA FR were 442.5 and 210.5 MTZ/cm(2), respectively. For full-NA FR, the PIH risk was 18.2% with cross-polarized images compared to 6.0% for mini-NA FR. This difference was statistically significant (P < 0.001). Improvement in skin texture, acne scarring, enlarged pores and overall pigmentation irregularity all reached statistical significance at last follow-up compared to baseline. There was no statistically significant difference in clinical efficacy between three full-NA FR and six mini-NA FR treatments.
CONCLUSIONS:
NA FR was effective and safe in Asians. By reducing the number of passes and the total treatment density, the risk of PIH could be reduced. Meanwhile, clinical efficacy could be maintained by increasing the total number of treatment sessions.
Lasers Surg Med. 2011 Jan;43(1):1-7.
A retrospective analysis of the management of acne post-inflammatory hyperpigmentation using topical treatment, laser treatment, or combination topical and laser treatments in oriental patients.
Ho SG1,
Yeung CK,
Chan NP,
Shek SY,
Kono T,
Chan HH.
BACKGROUND AND OBJECTIVES:
Post-inflammatory hyperpigmentation (PIH) is characterized by an acquired increase in pigmentation secondary to an inflammatory process, and is a commonly observed response to cutaneous injury in Fitzpatrick types III-VI patients.
OBJECTIVES:
To determine the effectiveness and safety of using topical treatment, laser treatment, or combination topical and laser treatments to treat acne PIH in Oriental patients.
METHODS:
This is a retrospective study of 34 randomly selected Chinese patients with acne PIH. They were divided into three groups, and treated with topical agents, 595 nm long pulsed dye laser and/or 1064 nm Q-switched Nd:YAG, or combination topical and laser treatments. An independent clinician assessed pre- and post-treatment photographs to determine efficacy and timing to visible and optimum improvement.
RESULTS:
There was significant global and focal improvement of acne PIH in patients in all three groups. However, no significant difference was found between the groups. An investigator global assessment showed improvement with all treatment modalities, with 70.6% moderate to marked improvement seen in the combination treatment group, compared to 55.6% in the laser only group, and 50% in the topical treatment only group. Visible and optimum improvement was seen by 3 months in majority of patients treated. One patient developed PIH as a result of laser treatment.
CONCLUSION:
Topical treatment, laser therapy, and combination topical and laser treatments all appear to be effective management strategies for acne PIH in Fitzpatrick types III and IV skin with little complications. Topical agents may be considered as first-line therapy for acne PIH, taking into consideration its effectiveness, ease of use and cost. Combined topical and laser therapy is also effective, and may be considered as second-line treatment.
Lasers Surg Med. 2011 Feb;43(2):108-13.
A comparison of Q-switched and long-pulsed alexandrite laser for the treatment of freckles and lentigines in oriental patients.
Ho SG1,
Yeung CK,
Chan NP,
Shek SY,
Chan HH.
BACKGROUND:
Q-switched (QS) lasers are effective in the treatment of freckles and lentigines in Type I and II skin, with minimal adverse effects. Long pulsed (LP) lasers have been proposed to be more suitable for treatment of darker skin types.
OBJECTIVES:
To investigate the efficacy and adverse effects of using QS or LP Alexandrite laser for the treatment of freckles and lentigines in Oriental patients.
METHODS:
A prospective split-face study of 20 Chinese patients who were randomly assigned to undergo a single QS (50 nanosecond) or LP (100 microseconds) laser treatment to either side of their face was carried out. Two blinded physicians assessed clinical efficacy using visual analogue scales of pre- and post-treatment photographs. Subjective assessment was evaluated using questionnaires which detailed the degree of pain, erythema and edema sustained during treatment, and improvement and satisfaction levels at 4, 8, and 12 weeks.
RESULTS:
There was statistically significant improvement in pigmentation (P < 0.05) in both groups throughout the study, with no statistical difference found between the groups. Postinflammatory hyperpigmentation was more frequently found after QS treatment (22%), compared to LP treatment (6%). Majority of patients reported moderate to marked improvement in pigmentation throughout the study with both pulse widths, and correspondingly high levels of satisfaction rates. More severe pain, erythema and edema were experienced during QS Alexandrite treatment.
CONCLUSION:
LP Alexandrite is quick and effective, and carries a lower risk of adverse effects than QS Alexandrite, for the removal of freckles and lentigines in darker skin types.
Lasers Surg Med. 2011 Jul;43(5):366-75.
Safety study of transcutaneous focused ultrasound for non-invasive skin tightening in Asians.
Chan NP1,
Shek SY,
Yu CS,
Ho SG,
Yeung CK,
Chan HH.
BACKGROUND AND OBJECTIVES:
Transcutaneous intense focused ultrasound has emerged as a novel technology for non-invasive skin tightening. The objective of this study was to evaluate the safety profile of a transcutaneous focused ultrasound device for the treatment of facial skin laxity in Asians.
MATERIALS AND METHODS:
The patients received one to three full-face treatments with the transcutaneous focused ultrasound device. Three transducers (7.0 MHz, 3.0 mm focal depth; 7.0 MHz, 4.5 mm focal depth; 4.0 MHz, 4.5 mm focal depth) were used to deliver a single pass of microthermal coagulation zones without any topical anesthetics. Standardized photos were taken at baseline and at each follow-up with the Canfield Visia CR system
® and were assessed by two independent physicians. Adverse effects were assessed up to 6 months post treatment. Subjective assessments in terms of pain and tolerability were also evaluated with patient questionnaires.
RESULTS:
Forty nine Chinese patients (skin types III-IV, mean age 53.3) completed a total of 68 treatment sessions. Transient erythema and edema were seen in the majority of patients. Focal bruising was present in up to 25% of treatment sessions. Two cases of post-inflammatory hyperpigmentation were seen on the forehead at 1-month post-treatment. One patient experienced focal twitching over the lower eyelid at 1-month follow-up, which was clinically consistent with hemifacial spasm and was unrelated to the ultrasound device. The degree of pain during treatment was recorded as severe in 54.4% of treatment sessions.
CONCLUSIONS:
Transcutaneous intense focused ultrasound appeared to be safe for non-invasive facial skin tightening in Asians. Adverse events were mild and transient. Pain control during treatment should be optimized. No serious permanent or delayed side effects were noted up to 6 months post treatment.
J Cosmet Laser Ther. 2012 Apr;14(2):74-80.
A retrospective analysis of the management of freckles and lentigines using four different pigment lasers on Asian skin.
Ho SG1,
Chan NP,
Yeung CK,
Shek SY,
Kono T,
Chan HH.
BACKGROUND:
The risk of post-inflammatory hyperpigmentation (PIH) is increased during freckles and lentigines treatment in Asians.
OBJECTIVE:
To determine the effectiveness and safety of using 595-nm long pulsed dye laser (LPDL), 755-nm LP Alexandrite laser, 532-nm QS Nd:YAG laser and 532-nm LP potassium-titanyl-phosphate (KTP) laser for the treatment of freckles or lentigines in Asian patients.
METHODS:
This is a retrospective study of 40 Chinese patients, who were divided into four groups based on treatment modality using four different pigment lasers.
Each patient attended between 1 and 4 treatments (mean of 1.8), at 4-6 weeks intervals, depending on clinical response. Lesional clearance and PIH were assessed by two independent clinicians.
RESULTS:
Statistically significant improvement of global and focal facial pigmentation was found after treatment with LPDL, QS Nd:YAG and LP KTP lasers.
No significant improvement was found after LP Alexandrite laser. PIH risk was 20% after LP Alexandrite treatment, 10% with QS Nd:YAG, and absent after LPDL and LP KTP treatment.
CONCLUSION:
A long pulse laser and small spot size appear to reduce the risks of lentigines treatment in darker skin types.
J Cosmet Laser Ther. 2013 Aug;15(4):200-6.
A retrospective study of the management of Chinese melasma patients using a 1927 nm fractional thulium fiber laser.
Ho SG1,
Yeung CK,
Chan NP,
Shek SY,
Chan HH.
BACKGROUND:
A new fractional photothermolysis device is used in our retrospective study to treat melasma in Chinese patients.
OBJECTIVES:
To evaluate the efficacy and safety of the 1927 nm fractional thulium fiber laser in the treatment of melasma in Chinese patients.
METHODS:
Eleven melasma patients who received treatment between November 2009 and May 2010 were included.
Photographic images at baseline and follow-up were assessed for clinical efficacy and complications by two independent and blinded physicians.
Questionnaires were also completed by patients.
RESULTS:
Significant MASI improvements were seen at 1 week, 1 month and 2 months, but not at 3 months. Patients' degree of satisfaction was high.
Significant improvement in skin texture and pore size was seen for up to 2 months and improvement in wrinkles for up to a month. There was no change in skin laxity. Main adverse effects seen were erythema, edema, and crusting in the early days. One patient developed PIH.
CONCLUSION:
The novel 1927 nm fractional thulium fiber laser is safe and effective in the management of melasma in Chinese patients for up to 2 months.
It is also useful in photo-rejuvenation. Complications were limited to erythema and edema in the early days, and transient PIH.
Australas J Dermatol. 2015 May;56(2):134-6
Eruptive disseminated Spitz naevus (EDSN) in a young girl of Indian origin.
Sharma N1,
Ho SY,
Bing TK,
McCormack C,
Scolyer R,
Lee J.
Eruptive disseminated Spitz naevus (EDSN) is a rare entity and has never been documented in a South-east Asian individual (of Indian origin) previously.
We report an adolescent with this condition which, to our knowledge, has only been previously reported a few times.
J Cutan Aesthet Surg. 2015 Jan-Mar;8(1):9-15.
Laser tattoo removal: A clinical update.
Ho SG1,
Goh CL1.
Techniques for tattoo removal have evolved significantly over the years.
The commonly used Quality-switched (QS) ruby, alexandrite, and Nd:YAG lasers are the traditional workhorses for tattoo removal.
Newer strategies using combination laser treatments, multi-pass treatments, and picosecond lasers offer promising results.
The tattoo color and skin type of the patient are important considerations when choosing the appropriate laser.
Standard protocols can be developed for the effective and safe treatment of tattoos.
