Visible action spectrum for melanin-specific selective photothermolysis

Role of Dermoscopy in Laser Therapy

Lasers have revolutionized the interventional dermatology field over the last two decades. Dermatologic conditions previously untreatable are now treated with lasers and lights. A large number of laser systems with advances in technologies have expanded applications of lasers for conditions like birth marks, acne scars, wrinkles, pigmentation, etc. Newer avenues and protocols are now set to treat skin conditions with lasers. The applicability of laser for any indication is dependent on laser tissue interaction which is well documented. For a successful outcome with laser therapy, a right end point of treatment should be achieved. The laser physician often adjusts parameters for laser therapy depending on tissue response, the ultimate aim being achieving optimum outcome with minimum side effects. Gadget based skin evaluation techniques are now an integral part of dermatology and are extending to interventional dermatology too. Application of dermoscopy before, during, and after lasers in various indications has been documented and reviewed. The representative cases highlighted in article emphasize the added dimension to non-invasive diagnostic capabilities of a dermatologist by enabling subsurface microscopy and enhancing therapy outcomes, and incorporation of these into daily practice offers value addition to not only evaluation but also gauging response to therapies. Use of dermoscopy before, during, and after laser therapies is an invaluable non-invasive tool to assess the right indication, initiate appropriate priming, achieve good end point, gauge untoward side effects, achieve good results, and engage patient confidentiality. Comparison of high magnification digital images is also enabled by digital videodermoscopy. Structured studies and protocols are needed to standardize the use of dermoscopy integrated with laser procedures.

Utilizing 808 nm laser for sensitizing of melanoma tumors to megavoltage radiation therapy

Melanotic melanoma has high content of melanin and laser can destroy melanin-containing cells through thermal effect. In this study, the therapeutic effect of 808 nm laser therapy was investigated on B16-F10 melanoma tumor growth and tumor-bearing mice survival time. In addition, as laser can destroy melanin as the main cause of melanoma radioresistance, the effect of laser administration to enhance radiation therapy efficacy at B16-F10 cancer cells was evaluated in vitro and in vivo. Laser therapy (1 W/cm² × 4 min) could cause significant (P < 0.05) inhibition of melanoma tumors' growth (~ 61%) and about three times increase of the tumor-bearing mice survival time in comparison with no-treatment group. In addition, the mice which were treated with 1 W/cm² × 4 min laser administration plus 6 Gy megavoltage radiation therapy exhibited ~ 68% lesser tumors' volume and 27 days increase of survival time in comparison with 6 Gy irradiated tumor-bearing mice. Also, significantly higher (P < 0.05) tumor necrosis percentage was observed at the histopathological slides of 1 W/cm² × 4 min laser + RT treated mice tumors (57 ± 12%) in comparison with radiation therapy group (31 ± 10%). Therefore, not only laser therapy can inhibit melanoma tumors' growth per se but also its combination with radiation therapy can cause a significant enhancement of radiation therapy efficacy. The laser administration can be used as a radiosensitizing method for melanotic melanoma radiation therapy.

Q-Switched 660-nm Versus 532-nm Nd: YAG Laser for the Treatment for Facial Lentigines in Asian Patients: A Prospective, Randomized, Double-Blinded, Split-Face Comparison Pilot Study

BACKGROUND

Q-switched (QS) 532-nm lasers are widely used to treat solar lentigines.

OBJECTIVE

To compare the efficacy and safety of 660-nm and 532-nm QS neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers in the treatment for lentigines in Asians.

MATERIALS AND METHODS

The halves of each face (randomly chosen) of 8 Korean Fitzpatrick Skin Type III-IV women with facial solar lentigines were treated with either 660-nm or 532-nm lasers. Pigmentation was measured objectively using a profilometric skin analysis tool and subjectively using the pigmentation area and severity index (PSI) score, global assessment of the aesthetic improvement scale (GAIS), and a patient satisfaction score at Weeks 4 and 8.

RESULTS

Seven patients completed the study. No significant differences were found in the PSI, GAIS, patient satisfaction score, and melanin average score between the lasers. The melanin average level was significantly reduced by the 660-nm laser but not the 532-nm laser at Week 8 compared with the baseline.

CONCLUSION

Both 660-nm and 532-nm QS Nd:YAG lasers effectively reduce pigmentation for up to 8 weeks with high patient satisfaction. The new 660-nm laser therefore increases the treatment options for lentigines in Asian skin.

Lasers for nevi: a review

A nevus is described as a benign, often pigmented, skin growth that can be congenital or acquired. Different types of nevi are located at different depths within the skin. Traditional treatments for nevi include topical treatments, dermabrasion, and excision, which are generally ineffective, invasive, and often result in scars and dyspigmentation. Lately, laser therapy has been used as an alternative. Based on the theory of selective photothermolysis, melanin can be specifically targeted, minimizing adverse effects and increasing effectiveness of laser treatments. Several types of lasers and lights have been studied for this purpose without a concise agreement as to which is the best. In general, quality-switched lasers are preferred for the treatment of pigmented lesions. However, there is controversy about this therapy because certain nevi may have malignant potential. This article serves as a comprehensive review of available laser treatments for nevi and discusses the appropriate measures that should be taken before and after laser therapy. Based on the reviewed literature, laser treatment has generally been proven to be a safe and effective therapy for nevi with minimal side effects.

The aesthetic applications of intense pulsed light using the Lumenis M-22 device

BACKGROUND

Fifteen years have passed since the first Intense Pulsed Light (IPL) devices were introduced into the market. A variety of devices that use light energy for aesthetic puposes are currently manufactured by several companies, and newer devices offering improved performance and features are periodically being introduced. Herein we present our experience with the MP-22 device (Lumenis Ltd., Yokneam, Israel) for cosmetic treatment of benign skin lesions.

PATIENTS AND METHODS

We collected patient data from all patients who received IPL and Nd:Yag laser treatments with the MP-22 over a one year period (Jan 2009-Jan 2010). The study group included 92 patients who were treated on the face, neck, trunk and hands. The main indications for treatment were lentigo and superficial vascular lesions. Patient age ranged from 16 to 72 years old, and 89 patients were female. Exclusion criteria for treatment were suspicion of skin cancer, isotretinoin treatment during the previous 6 months, and pregnancy. Satisfaction after treatment was evaluated by the patients on a scale ranging from 0 to 5, with 5 = excellent, 4 = very good, 3= good, 2= moderate improvement, 1= mild improvement and 0= no improvement.

RESULTS

Ninety-three percent of the patients were satisfied (rating 3, 4 or 5 on the above scale). Ninety-five percent of the patients had one or two treatment sessions. Of the treatments, 82 were on the face, two on the neck, four on the trunk and 13 on the dorsal aspect of the hands. Minor side effects such as erythema for longer than 24 hours and facial edema for more than one day were reported by 9 patients. Major complications such as scars, hyperpigmentation or hypopigmentation were not recorded. The fluence delivered varied from 14-18 J/cm(2).

CONCLUSION

IPL is an effective and safe method for skin treatments, namely removal of vascular and pigmented lesions.

Five parameters you must understand to master control of your laser/light-based devices

In this article, the authors review basic fundamental principles of light characteristics and their interaction with the target tissue. It is imperative for the practitioner to understand these concepts to deliver appropriate, efficacious, and safe phototherapeutic treatment for their patients. Once a diagnosis is made and a laser is chosen as a treatment tool, a basic knowledge and understanding of the physics and properties of light/tissue interaction is essential to allow practitioners to provide their patients with optimal results.

Evaluation of a hot-wire hair removal device compared to razor shaving

BACKGROUND AND OBJECTIVES

We describe a blinded, controlled, prospective clinical study of a hot-wire device promoted for hair removal and the reduction or delay of hair regrowth (no!no!, Radiancy, Inc., Orangeburg, NY) compared to a shaving control.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-two subjects were treated by trained clinical staff with the hot-wire device according to its Instructions for Use on the lower leg two times per week for 8 weeks. An adjacent site was shaved with a razor blade on the same schedule to provide a control. Subjects were followed for 3 months after the last treatment to study the durability of the results. Standardized high-resolution photographs were made at baseline, once a week during treatment, and monthly during the post-treatment follow-up period. Micro-tattoos were used to ensure treatments and photographs were reliably made in the same anatomical location from visit to visit. Both active and control sites were shaved prior to baseline and allowed to regrow for a fixed period of time before first treatment to provide a consistent and well-defined baseline hair condition. Quantitative hair counts were made by a third party from the photographs and standard statistical analysis was performed to look for differences between the active and control sites. Visual assessments and quantitative analysis was also performed on the photographs to see if there were any differences in hair thickness (diameter) and hair color between the active and control sites.

RESULTS

The results show that shaving and the hot-wire device are indistinguishable in short-term or long-term effect, based on both visual assessment of the photographs and statistical analysis of the hair counts. The control (shaving) had a mean baseline hair count of 79.4, which remained stable (74.8-84.3) during the 8 week-treatment phase and climbed substantially after stopping treatment to 98.8, 100.1, and 104.6 at 1, 2, and 3 months post-treatment, respectively. The active (hot-wire device) had a mean baseline hair count of 86.0 which remained fairly stable (81.7-95.1) during the treatment phase and then climbed substantially after stopping treatment to 104.0, 106.4, and 109.0 at 1, 2, and 3 months post-treatment, respectively. The difference in hair counts between the control and shaving showed that (a) in the treatment phase, shaving was slightly more effective at hair removal than the hot-wire device with weak statistical significance (P < 0.05 at 5 of 7 time points) and (b) in the follow-up phase, shaving and the hot-wire device were statistically indistinguishable (P = 0.252, 0.0972, and 0.230 at 1, 2, and 3 months, respectively). Likewise, the difference in percentage change from baseline in hair counts (which normalizes to baseline values) between the shaving control and hot-wire device is close to zero at every time point (-4.9% to +4.9%) and the t-test P-values are high (0.154< P < 0.890 over all the time points in the study and 0.360 < P < 0.890 during the 1, 2, and 3 month follow-up period), indicating no detectable difference between shaving and the hot-wire. In terms of hair characteristics, no difference in hair color or hair thickness was seen between the shaving control and the hot-wire sites in the treatment or follow-up period.

CONCLUSIONS

Relative to shaving, the hot-wire (no!no!) device does not produce lessened hair density, decreased hair re-growth rate, greater duration of effect, nor induce changes in hair thickness and color. We conclude that the hot-wire device does not offer any benefit as compared to shaving.

Q‐switched ruby laser irradiation on spotty pigmentation in the skin of the hairless dog

OBJECTIVE

To investigate macroscopically and histopathologically the dermatological changes after Q-switched ruby laser (QRL) irradiation with different exposure doses in UVB-induced pigmentation in hairless dogs.

METHODS

QRL irradiation with 3.0, 5.0 and 7.0 J/cm(2) was carried out on the UVB-induced spotty pigmentation in the skin of the hairless dog. Gross appearance was observed daily throughout this study. Histopathological examination was performed 1 day before QRL irradiation and 1 and 3 days and 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14 and 16 weeks after QRL irradiation.

RESULTS

Immediately after QRL irradiation, spotty pigmentation was removed. One week after QRL irradiation, re-epithelialization started from the margin of the irradiated sites. between 5 and 10 weeks after QRL irradiation, the skin color returned to normal and some portions showed recurrence of hyperpigmentation. Histopathologically, spotty pigmentation had a heavy deposition of melanin granules in the stratum basale, spinosum and corneum. One day after QRL irradiation, the skin showed destruction of melanin granules. Seven days after QRL irradiation, re-epithelialization began from the surroundings of the QRL-irradiated sites and the pilosebaceous units. The delayed process of re-epithelialization was dependent on the incident exposure dose with QRL. The repaired epidermis was devoid of melanin granules. By 5 weeks after QRL irradiation with 3.0 and 5.0 J/cm(2), the stratum basale and spinosum revealed a redistribution of melanin granules. In the sites of recurrent hyperpigmentation, the bases of the remaining hair follicles showed a notable increase in the reproduction of melanin granules. Melanin granules abundantly aggregated in the bottom portion of the nucleus in each epidermal cell.

CONCLUSION

These results revealed that hairless dogs were invaluable laboratory animals, which developed spotty pigmentation after successive UVB irradiation. In addition, UVB-induced spotty pigmentation in hairless dogs is useful for investigating the process of depigmentory treatment with QRL irradiation and recurrence of this lesion.

Treatment of idiopathic cutaneous hyperchromia of the orbital region (ICHOR) with intense pulsed light

BACKGROUND

Idiopathic cutaneous hyperchromia of the orbital region (ICHOR) does not have a clear etiopathogenesis. Genetic factors, increased melanin, prominent vasculature, and eyelid skin slackness seem to be involved.

OBJECTIVE

To evaluate individuals with ICHOR clinically and histologically, before and after treatment with high-energy pulsed light (HEPL), considering epidermal and dermal melanin, in order to evaluate HEPL efficacy in clearing away ICHOR, and 1 month and 1 year later to check whether improvement was maintained.

METHODS

Twelve individuals with ICHOR underwent clinical and histological evaluation before and after HEPL application, with photographic comparison. They underwent one to four HEPL sessions on the lower eyelid at approximately 30-day intervals. Melanin quantification by area, before and after treatment was performed by digital image morphometry.

RESULTS

Eyelid skin was significantly lightened (p = .24), and was maintained 1 year later with no ICHOR reincidence. All individuals (100%) showed postinflammatory hyperchromia (average 6-month duration), while 58.33% presented hypochromia (7-month duration). There was significantly decreased epidermal and dermal melanin after treatment.

CONCLUSION

HEPL was shown to be useful in clearing up ICHOR. This was maintained after 1 year. Epidermal and dermal histopathology showed decreased melanin following treatment. Longer follow-up is needed to evaluate possible later recurrence of ICHOR.

Lentigo maligna/lentigo maligna melanoma: current state of diagnosis and treatment

BACKGROUND

Lentigo maligna (LM) is a subtype of melanoma in situ that typically develops on sun-damaged skin. Presentation may be quite subtle and delayed diagnosis is common. Clinical margins are often ill defined. Histologic evaluation can be difficult due to the widespread atypical melanocytes that are present in the background of long-standing sun damage. Recurrence following standard therapies is common.

OBJECTIVE

To review the clinical features, histopathology, and treatment options for LM. Emphasis is placed on recent advances in the treatment of LM.

METHODS AND MATERIALS

Literature review.

RESULTS

The estimated lifetime risk of LM progressing to LM melanoma is 5%. Standard excision of LM with 5 mm margins is insufficient in 50% of cases. The recurrence rate with standard excision ranges from 8 to 20%. Mohs surgery and staged excision may offer better margin control and lower recurrence rates (4-5%). Estimates of recurrence rates following nonsurgical therapies such as cryosurgery, radiotherapy, electrodessication and curettage, laser surgery, and topical medications range from 20 to 100% at 5 years.

CONCLUSIONS

Adequate treatment of LM requires a comprehensive knowledge of the diagnostic features, histopathology, and treatment options. Surgical modalities with meticulous evaluation of tissue margins appears to offer the lowest rates of disease recurrence.

Diode-laser-induced cataract and iris atrophy as a complication of eyelid hair removal

PURPOSE

To caution about ocular risks of dermatologic diode laser, including cataract formation and iris atrophy.

DESIGN

Observational case report.

METHODS

A 63-year-old woman underwent diode epilation in the upper eyelid area without protective eye shields and experienced a sharp ocular pain during treatment of her left eye. She later presented with decreased vision in that eye and sensitivity to light.

RESULTS

Iris atrophy and a nuclear cataract were seen on examination. In the absence of any such observations at previous eye examinations and of any contributory ocular history, these findings were attributed to the diode laser treatment.

CONCLUSION

Diode laser epilation in the upper eyelid region could entail risks for intraocular structures, including cataractogenesis and iris atrophy.

Lasers in dermatology: four decades of progress

Advances in laser technology have progressed so rapidly during the past decade that successful treatment of many cutaneous concerns and congenital defects, including vascular and pigmented lesions, tattoos, scars, and unwanted hair-can be achieved. The demand for laser surgery has increased substantially by patients and dermatologists alike as a result of the relative ease with which many of these lesions can be removed, combined with a low incidence of adverse postoperative sequelae. Refinements in laser technology and technique have provided patients and practitioners with more therapeutic choices and improved clinical results. In this review, the currently available laser systems with cutaneous applications are outlined, with primary focus placed on recent advancements and modifications in laser technology that have greatly expanded the cutaneous laser surgeon's armamentarium and improved overall treatment efficacy and safety.

Intense pulsed light for the treatment of facial freckles in Asian skin

BACKGROUND

Freckles are melanotic lesions frequently seen on the face and other sun-exposed areas. Previously evaluation of the severity of freckles has relied on the ultimately subjective assessment of the doctor or patient. Intense pulsed light (IPL) is newly introduced to treat facial freckles in Asian skin.

OBJECTIVE

To determine the effectiveness of IPL treatment for Asian patients with freckled skin and to assess a new and objective method for evaluation of the severity of freckling and posttherapy improvement using an ultraviolet (UV)-sensitive camera and film.

METHODS

Thirty-six patients with freckles were enlisted. IPL treatment was administered to patients with freckles in 4-week sessions. Irradiation wavelength was controlled using cutoff filters ranging from 550 to 590 nm, with a fluence of 25-35 J/cm2, with single- or double-pulse illumination and a pulse width of 4.0 msec. The assessments of the physician and patient were compared with the objective dermatologic evaluation with black-and-white and UV photography used to derive two treatment parameters, cosmetic density of freckles (CDF) and freckles area and severity index (FASI), which are applicable in a clinical setting.

RESULTS

By the end of the study, two attending physicians assessed the results for 86.1% of the subjects as excellent or good, with 91.7% of the patients reporting that they were extremely or very satisfied. A statistically significant improvement in mean FASI score was demonstrated at 6 months after treatment compared with baseline (n = 36, p <.005; paired t-test). Mean overall improvement rate (n = 36), as determined from the difference in mean FASI score, was 63% at 12 weeks and 58% at 6 months.

CONCLUSION

IPL is an effective and safe treatment for facial freckles in Asian skin, with relatively few adverse effects and high satisfaction levels.

Intense pulsed light for melanocytic lesions

BACKGROUND

Few reports about melanocytic lesion treatment using intense pulsed light have been published.

OBJECTIVES

To evaluate the clinical results of diverse melanocytic lesions after treatment with an intense pulsed light source.

METHODS

Superficial and deep melanocytic lesions were treated by an intense pulsed light source with the following parameters: filters of 590, 615, and 755 nm, a fluence energy of 34-38 J/cm2, double mode, a pulse width of 3.8-4.5 msec, and a delay of 20 msec, at 4- to 8-week intervals. Two treatment sessions were applied to superficial lesions, while deep ones received four.

RESULTS

A clearance of 76-100% (excellent) was obtained for superficial lesions such as ephelides, epidermal melasma, and café au lait macules. Nevus spilus showed good clinical clearance (51-75%); however, deep lesions such as nevus of Becker, epidermal nevus, and mixed melasma showed an average clearance of less than 25%. Postinflammatory hyperpigmentation was observed in melasma.

CONCLUSION

Intense pulsed light is an effective treatment for superficial melanocytic lesions; however, those with a deep component improve only if repetitive treatment sessions are applied.

Hair reduction using a scanning 800 nm diode laser

BACKGROUND

Numerous lasers are currently available for hair removal, yet there are still few studies that have examined the role of fluence, light dose, hair color, and treatment number in laser hair reduction.

OBJECTIVE

To demonstrate the efficacy and safety of a scanning 800 nm diode laser for hair reduction.

METHODS

An 800 nm scanning diode laser was used to deliver 24, 38, or 48 J/cm2 to a 3 cm x 3 cm area of skin located on the back, groin/bikini area, or thigh in 36 adult patients with varying shades of brown or black hair. Patients received one to four treatments during the course of the study. Hair loss was evaluated at both 30 and 90 days after final treatment. Biopsies were obtained from 20 consenting patients.

RESULTS

Significant fluence-dependent hair reduction was demonstrated between treatment and control groups. At 48 J/cm2, the highest dose, a mean hair reduction of 43% was achieved 30 days after the final treatment, and 34% was achieved 90 days after the final treatment. Darker hairs were more effectively treated than lighter hairs.

CONCLUSIONS

Hair reduction can be safely and effectively achieved using a scanning 800 nm diode laser.

An in vivo trial comparing the use of different types of 532 nm Nd:YAG lasers in the treatment of facial lentigines in Oriental patients

BACKGROUND

Versapulse is a system that consists of four laser modalities and was developed with the aim of increasing cost-effectiveness. However, as these lasers share a common power supply, for the Q-switched (QS) Nd:YAG 532 nm laser a large spot diameter is necessary to lower the fluence to a suitable level. This can increase the risk of hyperpigmentation when used for the treatment of lentigines in dark-skinned patients.

OBJECTIVE

The aim of our study was to access the clinical efficacy and the complication rate of the Versapulse QS Nd:YAG 532 nm laser, the Versapulse long-pulsed Nd:YAG 532 nm laser (without the chill tip), and a conventional QS Nd:YAG 532 nm laser in the treatment of lentigines in Chinese patients.

METHODS

Thirty-four Chinese patients with lentigines were randomized to receive laser surgery, with one side of the face treated by one laser and the other side treated by a different system. Patients were monitored for 6 weeks to assess the degree of clearing, hyperpigmentation, hypopigmentation, and erythema. Assessments involved patients interviewed using a visual analog questionnaire and two blinded observers who evaluated the pre- and posttreatment clinical photographs.

RESULTS

The Versapulse QS Nd:YAG 532 nm laser was associated with a statistically higher risk of complications. The Versapulse long-pulsed Nd:YAG 532 nm laser was compatible with the conventional QS Nd:YAG 532 nm laser in terms of clinical efficacy and complication rates.

CONCLUSION

The Versapulse long-pulsed 532 nm laser is more effective and should be used instead of the Versapulse QS Nd:YAG 532 nm laser for the treatment of lentigines in dark-skinned patients.

Laser-assisted hair removal: side effects of Q-switched Nd:YAG, long-pulsed ruby, and alexandrite lasers

BACKGROUND

Laser-assisted hair removal has become popularized using wavelengths in both the red and infrared regions of the electromagnetic spectrum. These photoepilation devices target follicular melanin or an exogenous pigment placed within the follicle resulting in thermal damage to the hair follicle and shaft. However, melanocytes and keratinocytes located within the superficial layers of the skin also absorb red and infrared laser radiation. This may result in unwanted epidermal injury during the hair removal process.

OBJECTIVE

The purpose of this study was to examine a large patient population to determine the frequency of side effects using 3 different hair removal laser systems with various wavelengths, pulse durations, and treatment protocols.

METHODS

A retrospective chart review and digital photographic analysis of the side effects resulting from 900 consecutive laser-assisted hair removal treatments delivered over a 24-month study period, by means of either a Q-switched Nd:YAG laser with pretreatment wax-epilation and topical carbon solution, a long-pulse ruby laser with a contact cooling tip, or a long-pulse alexandrite laser are reported.

RESULTS

Treatment pain, erythema, edema, hypopigmentation and hyperpigmentation, blistering, crusting, erosions, purpura, and folliculitis were observed. The majority of undesirable tissue effects occurred on tanned skin or in Fitzpatrick skin phototypes III and higher. The ruby and alexandrite laser systems resulted in the majority of side effects seen. The effects of seasonal variations, anatomic treatment location, and sun exposure were striking within the ruby and alexandrite laser groups. No infections, scarring, or long-term complications occurred.

CONCLUSION

Laser-assisted hair removal is a safe procedure when patient characteristics such as skin type, anatomic location, and sun-exposed or tanned skin are considered during selection of laser treatment parameters. Lasers emitting wavelengths with high melanin absorption capabilities should be used in a conservative manner when treating patients with dark skin phototypes or suntans. No long-term complications, infections, or scarring occurred in this study population.

Theoretical considerations in laser hair removal

A systematic and logical approach for laser hair removal demands an understanding of its biologic and physical bases. This article presents an overview of hair anatomy and physiology followed by a mathematically nonrigorous review of tissue optics and thermal responses to laser irradiation. The reader is provided with a step by step approach to laser hair removal.

Failure of Q-switched ruby laser to eradicate atypical-appearing solar lentigo: report of two cases

Cutaneous lasers, including argon, Q-switched Nd:YAG, Q-switched ruby, Q-switched alexandrite, and short pulsed dye lasers, have been used to treat solar lentigines and other benign melanocytic lesions. However, the effects of these lasers at standard fluences on atypical melanocytic lesions have not been examined. We describe two patients in whom the Q-switched ruby laser failed to successfully treat clinically atypical-appearing solar lentigines. In both, clinically atypical-appearing melanocytic lesions were treated with excellent initial cosmetic results. In the first patient, the pigmentation returned several months after treatment and continued to increase in size and color. A biopsy specimen 30 months after Q-switched ruby laser therapy revealed a lentigo maligna melanoma. In the second patient, the lesion recurred 6 months after Q-switched ruby laser therapy, and a biopsy specimen 1 year after treatment showed an early lentigo maligna. Thus Q-switched ruby lasers and other cutaneous lasers capable of targeting melanin may be inadequate to eliminate lentigo maligna and other atypical melanocytic lesions completely. These cases emphasize the importance of careful clinical assessment before any laser surgery and the need to advise patients to return for evaluation should pigmentation return.

Melanin: a two edged sword?

Melanin is both photosensitizer and photoprotector. Skin cancer rates decrease with increasing constitutive pigmentation, yet the pigment has been shown to be photoreactive and capable of producing damaging reactive oxygen species. We utilized model systems of related cells or similar cell type that vary in constitutive and in induced pigment. Induction of eumelanin in Cloudman S91 mouse melanoma cells leads to less UV-induced killing and to less mutation induction at the ouabain locus (Na+, K(+)-ATPase). Pigmented mouse melanocytes, melan-b (brown) and melan-a (black) were slightly less sensitive than melan-c (albino) melanocytes to killing after UVC and UVA but were more sensitive to killing after UVB and UVB + UVA. Pigment had a small sensitizing effect on pyrimidine dimer DNA damage in both the melanoma cells and the melanocytes. The lack of consistency in these results suggests that intracellular pigment may disregulate the milieu intérieur resulting in end effects that are unrelated to the original genomic damage.

Comparison of the Q-switched alexandrite (755 nm) and Q-switched Nd:YAG (1064 nm) lasers in the treatment of benign melanocytic nevi

BACKGROUND

A variety of pigmented lesions have been shown to be effectively treated with several pigment-specific laser systems currently available. There has been recent evidence to indicate that they may also be useful in the treatment of melanocytic nevi.

OBJECTIVE

To compare the clinical and histologic effects of the Q-switched (QS) alexandrite (755 nm) and Nd:YAG (1064 nm) lasers in the treatment of melanocytic nevi.

METHODS

Eighteen patients received three QS alexandrite and Nd:YAG laser treatments to either half of a large nevus or to two small adjacent nevi. Tissue biopsies were obtained for histologic examination. Degree of clinical improvement was determined by comparative photographic global assessment scores. The amount of melanin present within the nevi before and after laser irradiation was measured by reflectance spectrometry.

RESULTS

Clinical global assessment scores were significantly reduced in all QS alexandrite and QS Nd:YAG laser-treated nevi after three treatments. Melanin reflectance spectrometry scores improved after the first laser treatment only. Histologically, a significant reduction in epidermal pigmentation and melanocytes were observed following laser irradiation with either QS system.

CONCLUSION

Both the QS alexandrite and Nd:YAG laser systems resulted in significant improvement (lightening) of treated nevi. The QS alexandrite laser produced slightly better results using the parameters outlined.

Thermal relaxation of port-wine stain vessels probed in vivo: the need for 1-10-millisecond laser pulse treatment

Although thermal relaxation times of cutaneous port-wine stain microvessels have been calculated and used to formulate laser selective photothermolysis, they have never been measured. A scheme to do so was devised by measuring the skin response to pairs of 585-nm dye laser pulses (250-360 microseconds each) as a function of the time interval between the two pulses, in five volunteers with port-wine stains. After a pump pulse delivering 80% of the fluence necessary for causing purpura, the fluence of a second probe pulse necessary to cause purpura was determined and was found to increase with the interval between the two pulses, in a manner consistent with thermal diffusion theory. Biopsy specimens were obtained from four of the five subjects to examine the nature and extent of vessel damage and to measure the port-wine stain vessel diameters. Using diffusion theory, the thermal relaxation time was calculated based on the measured vessel diameters. These calculated values are consistent with the increase in radiant exposure (fluence) of the probe pulse necessary to induce purpura for longer time delays. Two simple models for thermal relaxation of port-wine stain vessels are presented and compared with the data. The data and histologic assessment of the vessel injury strongly suggest that pulse durations for ideal laser treatment are in the 1-10-millisecond region and depend on vessel diameter. No dermatologic lasers presently used for port-wine stain treatment operate in this pulse width domain.

Treatment of nevus of Ota by the Q-switched alexandrite laser

BACKGROUND

The Q-switched alexandrite laser (755 nm, 100 nanoseconds) selectively targets and destroys cutaneous pigment such as that found in dermal pigmented lesions and tattoos. The nevus of Ota is a benign dermal melanocytic lesion, which, due to its large size and periocular location, has been notoriously difficult to treat. Utilizing the principles of selective photothermolysis, the alexandrite laser could effect an excellent treatment for nevus of Ota.

OBJECTIVE

To report the effectiveness of the Q-switched alexandrite laser in treating nevus of Ota.

METHODS

Seven patients with nevus of Ota were treated with the Q-switched alexandrite laser (755 nm, 100 nanoseconds) with energy densities ranging from 4.75 to 7.0 J/cm2 at 8-12-week intervals. Response to therapy was evaluated through independent observation and rating of sequential photographs by two blinded observers. Histologic examinations of lesional skin biopsies before and after completion of laser treatments were performed.

RESULTS

An average of two laser treatments were required to effect an average clinical improvement of 50%. Five patients showed 100% lesional clearance after an average of five treatments. No scarring, textural changes, or pigmentary side effects were observed in treated skin. Histology of laser-irradiated lesions revealed elimination of upper dermal pigmentation without epidermal disruption, and rare melanophages and pigmented spindle cells in the deep reticular dermis. No lesional recurrences were observed up to 1 year following treatment.

CONCLUSION

The Q-switched alexandrite laser can effectively eliminate nevus of Ota without untoward side effects, such as scarring.

Selective targeting of trabecular meshwork cells: in vitro studies of pulsed and CW laser interactions

The purpose of the present study was to selectively target pigmented trabecular meshwork cells without producing collateral damage to adjacent non-pigmented cells or structures. The ability to selectively target trabecular meshwork cells without coagulation, while preserving the structural integrity of the meshwork, could be a useful approach to study whether the biological response of non-coagulative damage to the trabecular meshwork and trabecular meshwork cells is similar to that seen with coagulative damage to the trabecular meshwork which occurs with argon laser trabeculoplasty. This approach also may be useful to non-invasively deplete trabecular meshwork cells while preserving the structural integrity of the trabecular meshwork in an animal model. A mixed cell culture of pigmented and non-pigmented trabecular meshwork cells were irradiated with Q-switched Nd-YAG and frequency-doubled Nd-YAG lasers, microsound pulsed dye-lasers, and an argon ion laser in order to define a regime where laser absorption would be confined to pigmented trabecular meshwork cells, thereby permitting selective targeting of these cells without producing collateral thermal damage to adjacent non-pigmented cells. Pulse durations ranged from 10 nsec to 0.1 sec. A fluorescent viability/cytotoxicity assay was used to evaluate laser effects and threshold energies, and cells were examined morphologically by light and TEM. Selective targeting of pigmented trabecular meshwork cells was achieved with pulse durations between 10 nsec and 1 microsec and 1 microsec without producing collateral thermal or structural damage to adjacent non-pigmented trabecular meshworks cells when examined by light and transmission electron microscopy. Pulse durations greater than 1 microsec resulted in non-selective killing of non-pigmented trabecular meshwork cells. Threshold radiant exposures were as low as 18 mJ cm-2, and increased at longer wavelengths, longer pulse durations and lower melanin contents within the cells. It is concluded that selective targeting of pigmented trabecular meshwork cells can be achieved using pulsed lasers with low threshold radiant exposures avoiding collateral thermal damage to adjacent non-pigmented trabecular meshwork cells. This approach can be readily applied in vivo.

Treatment of nevus of Ota with the Q-switched ruby laser

BACKGROUND

Nevus of Ota is a benign bluish or gray-brown lesion of the eye and the surrounding skin that has been reported to occur in about 1 in 200 people in Japan. Prior treatments have either been ineffective or caused scarring. The Q-switched ruby laser can produce very short high-energy pulses and can selectively target cells that contain pigment, such as dermal melanocytes.

METHODS

We treated the skin lesions of 114 patients (25 male and 89 female) with nevi of Ota with a Q-switched ruby laser set to deliver pulses of 6 J per square centimeter of body-surface area at a wavelength of 694.3 nm, with a pulse duration of 30 nanoseconds. The interval between treatments ranged from three to four months. Five dermatologists who were not familiar with the patients independently compared a full set of pretreatment and post-treatment photographs of each patient and determined the percentage of pigment lightening of the affected areas using standard criteria.

RESULTS

Of the 35 patients who received four or five treatments, 33 had an excellent response (lightening of 70 percent or more), and 2 had a good response (lightening of 40 to 69 percent). Of the 31 patients who received three treatments, 4 had an excellent response, 26 a good response, and 1 a fair response (lightening of 10 to 39 percent). Of the 25 patients who received two treatments, 2 had an excellent response, 16 a good response, and 7 a fair response. Of the 23 patients who received one treatment, 3 had a good response, 13 a fair response, and 7 no response (lightening of 9 percent or less). No patient had hypertrophic or atrophic scarring; eight patients had postinflammatory hyperpigmentation for up to two months after the first treatment.

CONCLUSIONS

Selective photothermolysis with the Q-switched ruby laser is a safe and effective method for lightening nevi of Ota. Multiple treatments increase the response rate.

Optical and thermal characterization of natural (Sepia officinalis) melanin

The optical properties and the thermal diffusivity of natural cuttlefish (Sepia officinalis) melanin have been measured. The optical absorption and scattering properties of melanin particles were determined at 580 nm and 633 nm, using photometric and photothermal techniques. For the photometric studies, the absorption and the transport scattering coefficients were determined from the measurements of diffuse reflectance and transmittance. The scattering anisotropy was obtained from an additional measurement of the total attenuation coefficient and independently obtained by goniometry. For photothermal studies, pulsed photothermal radiometry was used to deduce the absorption and transport scattering coefficients via a model based on optical diffusion theory. Pulsed photothermal radiometry was also used to provide the thermal diffusivity of solid melanin pressed pellets.

Nevus of Ota: treatment with high energy fluences of the Q-switched ruby laser

BACKGROUND

The nevus of Ota is a benign dermal melanocytic lesion that has previously proved difficult to treat. Recently, the Q-switched ruby laser has been reported to be successful in treating benign pigmented lesions and tattoos.

OBJECTIVE

Our study evaluates the treatment of 16 patients with nevus of Ota with the Q-switched ruby laser (694 nm).

METHODS

Sixteen patients with nevus of Ota were treated with the Q-switched ruby laser with a pulse width of 28 nsec and energy fluences ranging from 7.5 to 10 J/cm2. Response to treatment was assessed by an independent investigator with photographs.

RESULTS

The average number of treatments was 3.8 per patient. After two treatments, 44% of patients showed a 50% or greater improvement. After three treatments, 85% of patients showed a 50% or greater improvement; after four treatments, 100% of patients showed 50% or greater improvement. No patients had permanent textural changes or scarring.

CONCLUSION

High-energy fluences of the Q-switched ruby laser lead to significant improvement without scarring of nevus of Ota after a few treatments.

510-nm pigmented lesion dye laser. Its characteristics and clinical uses

BACKGROUND

Benign pigmented lesions are of a cosmetic concern to many individuals. Numerous treatments exist, including several types of lasers. The Candela 510 nm pigmented lesion dye laser has recently been added to this armamentarium. It is designed specifically for the treatment of superficial pigmented lesions while significantly decreasing the risk of scarring and prolonged hypopigmentation.

OBJECTIVES

To describe the characteristics of the Candela pigmented lesion dye laser and report on the therapeutic outcome of patients treated for actinic lentigines, café-au-lait macules, melasma and red tattoos by one of the authors (RCG).

METHODS

The Candela 510 nm pigmented lesion dye laser was used to treat solar lentigines, café-au-lait macules, melasma and red tattoo.

RESULTS

Excellent outcomes resulted on facial and hand lentigines (89% and 88% of patients had greater than 75% clearing, respectively), but often required more than one treatment. Lentigines located on the upper extremities and trunk improved less dramatically. Immediate greying occurred universally. Bruising was often noted. Treatment failures have been observed especially in treating lentigines located on the lower extremities. Café-au-lait macules responded inconsistently, with facial lesions giving the best results. Melasma responded poorly, often with hyperpigmentation. Three red tattoos cleared. Treatment failure may be related to inaccurate clinical assessment of pigment depth or regrowth of the lesion. Several cases are presented to demonstrate clinical and histologic effects of the laser.

CONCLUSION

The Candela 510-nm pigmented lesion dye laser is an effective treatment for superficial pigmented lesions. Its associated morbidity is minimal.

Laser treatment of benign pigmented epidermal lesions using a 300 nsecond pulse and 510 nm wavelength

Sixty-five patients having a total of 492 lesions were treated with the Candela pigmented lesion dye laser (510 nm, 300 ns). Lesions treated included café-au-lait macules, lentigines, seborrheic keratoses, and postinflammatory hyperpigmentation. Fluences varied from 2.0 J/cm2 to 3.5 J/cm2, but averaged 2.25 J/cm2. Response was good to excellent after one treatment with 40-50% completely clearing and an additional 33% clearing by 75% or more. Repeated treatments were capable of clearing residual lesions. Histologic examination revealed vacuolization of melanin-containing cells and suprabasilar vesicles. The only adverse sequelae were transient hypopigmentation and hyperpigmentation, which resolved in 4 to 6 months.

Pulse duration effects on cutaneous pigment

Melanin, an endogenous chromophore in pigment containing cells in skin, is being specifically altered by lasers using the principle of selective photothermolysis (SPT). This implies that a combination of specific laser parameters of wavelength, pulse duration, spotsize, and energy density are required to confine the delivered laser energy to the targeted cells alone. Because the bulk of cutaneous pigment is localized to epidermal basal cells, pigmentary incontinence has been found to occur in skin exposed to laser irradiation. This study demonstrates that pulse duration or exposure time of the laser affect the severity of pigmentary incontinence induced. Pigment granules are more abundant, aggregated, and located deeper in the dermis following exposure to 500 nsec pulse duration than 100 nsec at a wavelength of 504 nm. This relationship appears to be independent of the laser energy density used.

Dohi memorial lecture. Laser medicine and laser dermatology

As laser devices become smaller, more reliable, and less expensive, dermatology will benefit from new laser-based therapeutic and diagnostic methods. Already there are simple, non-scarring, and relatively painless techniques for removal of pigmented lesions, tattoos, and vascular lesions. Because much of the basic and applied research in photobiology is grounded in dermatology research, dermatology will continue to be a major contributor to advances in laser medicine and photomedicine. An increase in understanding and ability to manipulate laser-tissue interactions will add greatly to the future of medicine and surgery, especially in applications utilizing pulsed lasers. We are learning how to: 1) vary wavelength, pulse duration, and energy to influence the nature of microscopic injury and host response in order to achieve a net therapeutic benefit; 2) utilize exogenous chromophores to increase the selection of targets for laser radiation; and 3) capture optical technology developed for industrial and military use, in order to benefit mankind with new medical and surgical techniques.