Low-fluence carbon dioxide laser irradiation of lentigines

Low-fluence carbon dioxide (CO2) laser irradiation of skin has previously been shown to induce damage limited primarily to the epidermis. To evaluate whether this technique was therapeutically effective for pigmented epidermal lesions, ten lentigines caused by methoxsalen and ultraviolet light therapy were treated in one patient using the CO2 laser at fluences ranging from 3.0 to 7.7 J/cm2 for 0.1-s exposures with 4.5-mm spot size. Based on substantial clearing in seven of ten lesions treated, 146 solar lentigines were treated in five patients at fluences of 3.0, 3.7, or 4.4 J/cm2. Biopsies were performed on a total of 30 lesions immediately and 24 hours, seven days, and six weeks after irradiation. Of 125 lesions followed up clinically for six weeks, 12 cleared completely, 81 lightened substantially, and 28 remained unchanged. Only two demonstrated atrophic change. Hyperpigmentation or hypopigmentation did not occur. All lesions that improved had been treated at 3.7 or 4.4 J/cm2. Immediate histologic injury consisted of vacuolar and spindly change and subsequent vesiculation limited to the basilar epidermis. Twenty-four hours later there was epidermal necrosis with regeneration, 0.1 mm of dermal basophilia and stromal condensation, and a mild inflammatory infiltrate. These alterations were dose-dependent, with near complete epidermal necrosis and superficial dermal involvement at the highest fluence, and only focal epidermal necrosis at the lowest. At seven days, epidermal regeneration was complete with traces of melanin remaining in keratinocytes. Melanophages first appeared at seven days and persisted at six weeks, by which time the inflammatory infiltrate had cleared. No lentiginous proliferation was evident and epidermal pigmentation had become normal. Low-fluence CO2 laser irradiation is an effective means of damaging the epidermis with only minimal dermal change. This mode of therapy is an effective way to lighten the pigmentation of lentigines without substantial scarring.     

Fractionated CO2 laser skin rejuvenation

Fractional photothermolysis has been reported in the literature to improve both the pigmentary and textural changes associated with photoaging. The objective of the study was to review the literature of non-ablative fractional laser (NAFL) and ablative fractional laser (AFL) resurfacing for the treatment of photoaging. This is a review of the Medline literature evaluating NAFL and AFL for photoaging. Review of the literature supports the use of NAFL and AFL as safe and effective treatments for photoaging. It is likely that the controlled, limited dermal heating of fractional resurfacing initiates a cascade of events in which normalization of the collagenesis/collagenolysis cycle occurs. The advent of fractionated resurfacing for the treatment of photoaging is a significant advance over ablative laser resurfacing treatments, which were complicated by prolonged erythema, delayed onset hypopigmentation, and scarring.     

Resveratrate protects human skin from damage due to repetitive ultraviolet irradiation

Background Ultraviolet (UV) exposure results in the production reactive oxygen species. Resveratrol has attracted considerable attentions owing to its natural abundance and multiple biological effects. Objective To investigate the protective effects of resveratrate against damage to human skin induced by repetitive solar simulator ultraviolet radiation (ssUVR). Materials and methods Fifteen healthy volunteers were enrolled, and six sites on the non‐exposed dorsal skin of each volunteer were marked for study. Sites 1–4 were exposed to ssUVR at a dosage of 1.5 minimal erythema dose for consecutive 4 days. Immediately after each exposure, one test material (resveratrate + antioxidant, antioxidant, resveratrate, vehicle) was applied to one of the four sites. Site 5 and site 6 were marked as positive control site (UVR only) and baseline control site (no treatment, no UVR). L*a*b values were assessed preprocedure and postprocedure. Skin biopsies were taken 24 h after the last irradiation. The specimens were stained to determine the number of sunburn cells and melanin content melanin. Results On resveratrate treated sites, erythema was barely seen with only slight decrease of L value and insignificant increase of *a value. Furthermore, resveratrate significantly inhibited sunburn cell formation, and decreased Fontana‐Masson staining in skin samples. Conclusions Resveratrate exerts protective effects against repetitive ssUVR‐induced sunburn and suntan.     

CO2 laser therapy of verrucous epidermal nevus

INTRODUCTION: Verrucous epidermal nevus are benign epidermal hyperplasias. Their treatments are disappointing because of recurrences and anaesthetic scars. The aim of this study was to evaluate the efficacy of continuous carbon dioxide laser in the treatment of verrucous epidermal nevus. MATERIAL AND METHODS: It was a retrospective study concerning all patients treated for epidermal verrucous nevus by carbon dioxide laser from 1991 to 2003. Several criteria were evaluated by the patients, a dermatologist and a staff (external observers). Aesthetic result, recurrences, pain due to treatment and global result were evaluated by the patients when they came back. RESULTS: Twenty-one patients (12 F and 9 M), medium age 20.4, were evaluated with a 40.4 months follow-up (7 to 165 months). The epidermal verrucous nevus was situated on the neck or on the head for 62% of them (n = 13). Among these 21 patients, 86% (n = 19) estimated their skin as "cured" or "nearly normal" or "much improved". The rate was the same for the dermatologist. As for the staff, thanks to photos, only 53% of results were satisfying. The recurrences were never complete, but moderate in 38% of patients. Five patients, medium age 12,5, had hypertrophic scars. Among them, three were only partially hypertrophic. DISCUSSION: A literature review has been made. Our satisfaction rates (nearly 90%) were slightly higher than other studies rates using carbon dioxide laser (74%) or other types of lasers (87%). The medium follow-up was longer than the one of other laser CO2 studies (26.7 months) or other lasers studies' (15.8 months). This study shows that continuous wave carbon dioxide laser is an easy and effective treatment of verrucous epidermal nevus. Aesthetic results are satisfying but moderate recurrences often occur. To prevent hypertrophic scars, we suggest to exclude teenagers.     

Cutaneous tissue repair following CO2 laser irradiation

We studied the mechanism of repair following exposure of normal skin to the CO2 laser in a focused mode. Exposed areas were biopsied at 0, 24, 48 h; 1, 2 weeks; 1, 2 1/2 months (pulse width varying from 0.1 to 1.0 s) after irradiation. The initial pattern was a V-shaped zone of cauterized collagen with a central crevice, the depth of which correlated with the total energy applied. The epidermal changes consisted of transepidermal cauterization and basal vacuolar changes lateral to the site of impact. Over a period of 1 week, the wound crevice decreased in depth and width and the central margins of the zone of cauterized collagen approximated. The cauterized collagen was extruded and was noted in the epidermal crust; minimal granulation tissue was present. Biopsies at later time periods showed formation of granulation tissue and retention of small amounts of necrotic collagen; the process of collagen extrusion was largely prevented by suturing. These observations show that dermal contraction and necrotic collagen extrusion are important components of initial tissue repair following limited dermal destruction produced by CO2 irradiation.     

DNA damage in cultured human skin fibroblasts exposed to excimer laser radiation

Ultraviolet excimer lasers are being considered for use in a variety of refractive and therapeutic procedures, the long-term biologic consequences of which are unknown. The effect of sublethal doses of 193-nm laser radiation on cellular DNA was examined in cultured human skin fibroblasts. In contrast to 248 nm, treatments with the 193-nm laser radiation below 70 J/m2 did not cause significant pyrimidine dimer formation in the skin cells. This was indicated by the lack of excision repair activities (unscheduled DNA synthesis assay), and further demonstrated by direct analysis of pyrimidine dimers in DNA from irradiated cells. However, a low level of unscheduled DNA synthesis could be detected following irradiation at 193 nm with 70 J/m2. Both the 193-nm and 248-nm radiation were able to induce chromosomal aberrations, as indicated by a micronucleus assay. A dose-dependent increase in micronuclei frequency was observed 48 and 72 h after laser irradiation. These results indicate that exposure of actively replicating human skin fibroblasts to sublethal doses of either 193- or 248-nm laser radiation can result in genotoxicity.     

Resurfacing CO2 laser treatment of linear verrucous epidermal nevus

The term linear epidermal nevus (LVEN) refers to benign hyperplasia of the epidermis. Three types of LVEN can be distinguished: localized, systemic and inflammatory form. All have in common resistance to treatment and risk of recurrence. We report the observations of 5 patients with inflammatory linear verrucous epidermal nevus and 5 patients with linear verrucous epidermal nevus. Management by superpulsed CO2 laser was performed as follows: test treatment, completed by removal of the lesion in one or more sessions. Treatment was effective in all cases but 2. Satisfactory cosmetic results were obtained; slight hyperpigmentation, transitory desquamation and erythematous papules were observed. There was no recurrence in two years follow-up. We suppose that for the two patients with recurrence, our treatment failure is due to the lower laser parameters used in these patients compared to the others, because of their younger age.     

Effect of skin temperature on selective vascular injury caused by pulsed laser irradiation

The effect of skin temperature on vascular-specific injury caused by pulsed laser irradiation was examined. Ten healthy human volunteers were exposed to 1.5 microsecond pulses from a dye laser tuned to 577 nm. Compared to normothermic conditions (33 degrees C skin temperature) significantly more laser energy (p less than 0.01) was required to produce grossly visible purpura when the skin was cooled to 20 degrees C or heated to 40 degrees C. Histologically, laser-induced damage was confined to blood vessels at all three skin temperatures studied. At purpura threshold dose, there was intravascular agglutination without extravasation of red blood cells at 20 degrees C whereas at 33 degrees and 40 degrees C there was extravasation of red blood cells.     

Re-epithelialization of the skin following CO 2 laser resurfacing

Wound healing following CO 2 laser resurfacing of the face is a complex process which must involve a rapid replacement of the ablated epidermis to protect the underlying structures in the skin from desiccation and deeper injury. The majority of cells that regenerate the epidermis come from the hair follicles, and cell movement out of the follicles is monitored using immunofluorescence with antibodies to keratin 17, an intermediate filament protein expressed in the migrating front of cells. This migration is enhanced with occlusive dressings used immediately after the resurfacing procedure. Skin biopsies have been examined at multiple time points following resurfacing, and re-epithelialization begins by 48 h in skin that has been occluded. Skin that has been left open with no treatment forms an eschar and has no keratinocyte migration at 48 h, thus displaying delayed wound healing.     

Effects of cryogen spray cooling and high radiant exposures on selective vascular injury during laser irradiation of human skin

BACKGROUND: Increasing radiant exposure offers a means to increase treatment efficacy during laser-mediated treatment of vascular lesions, such as port-wine stains; however, excessive radiant exposure decreases selective vascular injury due to increased heat generation within the epidermis and collateral damage to perivascular collagen. OBJECTIVE: To determine if cryogen spray cooling could be used to maintain selective vascular injury (ie, prevent epidermal and perivascular collagen damage) when using high radiant exposures (16-30 J/cm2). DESIGN: Observational study. SETTING: Academic hospital and research laboratory. PATIENTS: Twenty women with normal abdominal skin (skin phototypes I-VI). INTERVENTIONS: Skin was irradiated with a pulsed dye laser (wavelength = 585 nm; pulse duration = 1.5 milliseconds; 5-mm-diameter spot) using various radiant exposures (8-30 J/cm2) without and with cryogen spray cooling (50- to 300-millisecond cryogen spurts). MAIN OUTCOME MEASURE: Hematoxylin-eosin-stained histologic sections from each irradiated site were examined for the degree of epidermal damage, maximum depth of red blood cell coagulation, and percentage of vessels containing perivascular collagen coagulation. RESULTS: Long cryogen spurt durations (>200 milliseconds) protected the epidermis in light-skinned individuals (skin phototypes I-IV) at the highest radiant exposure (30 J/cm2); however, epidermal protection could not be achieved in dark-skinned individuals (skin phototypes V-VI) even at the lowest radiant exposure (8 J/cm2). The red blood cell coagulation depth increased with increasing radiant exposure (to >2.5 mm for skin phototypes I-IV and to approximately 1.2 mm for skin phototypes V-VI). In addition, long cryogen spurt durations (>200 milliseconds) prevented perivascular collagen coagulation in all skin types. CONCLUSIONS: Cryogen spurt durations much longer than those currently used in therapy (>200 milliseconds) may be clinically useful for protecting the epidermis and perivascular tissues when using high radiant exposures during cutaneous laser therapies. Additional studies are necessary to prove clinical safety of these protocols.     

Fractional CO2 laser treatment for a skin graft

Skin grafts are widely used in reconstructive and plastic surgery, leaving an inevitable scar appearance on the body, affecting the quality of life of the patients. Fractional ablative lasers have become a leading procedure for the treatment of acne and burn scars. We report a case of a skin graft showing excellent improvement in overall appearance after three sessions of fractional CO₂ laser. The undamaged tissue left between the microthermal treatment zones is responsible of collagen formation and reepithelialization. Remodeling and collagen formation are observed even 6 months after a fractional CO₂ laser session.     

Bilateral epidermal nevi in the external auditory canals treated with CO2 laser

Epidermal nevi are benign hamartomas of the epidermis and adnexal structures of the skin. We present the case of epidermal nevi in the bilateral external auditory ear canals of an otherwise healthy 23-year-old woman treated with CO₂ laser ablation.     

A study of Q-switched Nd:YAG laser irradiation and paracrine function in human skin cells

BACKGROUND AND OBJECTIVES: This preliminary laboratory-based study looks at the paracrine release from human skin cells subject to sublethal Q-switched Nd:YAG 532 nm laser irradiation. STUDY DESIGN/MATERIALS AND METHODS: Human dermal fibroblast and keratinocyte cultures were exposed to sublethal energy using the Nd:YAG 532 nm laser. Altered gene expression was then screened using RT-PCR for a range of paracrine factors known to affect melanogenesis, basic fibroblast growth factor (b-FGF), hepatocyte growth factor (HGF), stem cell factor (SCF), melanocyte stimulating hormone (MSH), endothelin-1 (ET-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and protease-activated receptor-2 (PAR-2). Enzyme-linked immunosorbent assay (ELISA) was used to confirm protein production. Conditioned medium was used to assess altered melanogenesis in a melanoma cell line. Results: Fibroblasts exposed to sublethal radiation showed upregulation of b-FGF, HGF and SCF. This contrasts with keratinocytes which showed upregulation of IL-6. Elevated protein levels of b-FGF and SCF were confirmed by ELISA assay. Conditioned fibroblast medium was shown to stimulate melanogenesis in a melanoma cell line. CONCLUSIONS: This preliminary laboratory study reports, for the first time, specific gene upregulation using the Q-switched Nd:YAG 532 nm laser.     

A Chinese experience of fractional Ultrapulsed CO2 laser for skin rejuvenation

Abstract

Background and objectives: The ablative fractional CO₂ laser has been successfully used in treating photoaged skin in the Caucasian population. However, its application in Asian skin has not been widely reported. The purpose of this study is to observe the efficacy and safety of the protocol ‘ActiveFX’ for photodamaged facial skin in Chinese patients. Methods: A non-sequential fractional ultrapulsed CO₂ laser with specific settings is used in addition to a new computer pattern generator (CPG). Twenty patients received a single-session, single-pass, ablative fractional treatment on a split face. The patients were evaluated at baseline, and 1 and 3 months (M1, M3) after the treatment using a quartile grading scale. They were also asked to assess their overall satisfaction using a 4-point scale. The improvement of the coarse wrinkles was also quantitatively analyzed with a 3D in vivo imaging system. Results: At M1 and M3, the blinded investigator rated global improvement as 2.8 ± 0.95 and 3.00 ± 0.73, which was consistent with the patients' assessment (2.55 ± 0.83 at M1 and 3.15 ± 0.88 at M3). The roughness analysis (Rz) demonstrated a significant decrease in periorbital wrinkles (p < 0.0001). Minimal and reversible adverse side effects and rapid healing were noted. Conclusions: Non-sequential fractional ultrapulsed CO₂ laser resurfacing (ActiveFX) is considered an excellent treatment modality for photodamaged Chinese facial skin.     

Q-switched ruby laser irradiation of normal human skin. Histologic and ultrastructural findings.

The Q-switched ruby laser is used for treatment of tatoos. The effects of Q-switched ruby laser pulses on sun-exposed and sun-protected human skin, as well as senile lentigines, were investigated with clinical observation, light microscopy, and transmission electron microscopy. A pinpricklike sensation occurred at radiant exposures as low as 0.2 J/cm2. Immediate erythema, delayed edema, and immediate whitening occurred with increasing radiant exposure. The threshold for immediate whitening varied inversely with skin pigmentation, ranging from a mean of 1.4 J/cm2 in lentigines to 3.1 J/cm2 in sun-protected skin. Transmission electron microscopy showed immediate alteration of mature melanosomes and nuclei within keratinocytes and melanocytes, but stage I and II melanosomes were unaffected. Histologically, immediate injury was confined to the epidermis. There was minimal inflammatory response 1 day after exposure. After 1 week, subthreshold exposures induced hyperpigmentation, with epidermal hyperplasia and increased melanin staining noted histologically. At higher radiant exposures, hypopigmentation occurred with desquamation of a pigmented scale/crust. All sites returned to normal skin color and texture without scarring within 3 to 6 months. These observations suggest that the human skin response to selective photothermolysis of pigmented cells is similar to that reported in animal models, including low radiant exposure stimulation of melanogenesis and high radiant exposure lethal injury to pigmented epidermal cells.     

Micro-island damage with a nonablative 1540-nm Er:Glass fractional laser device in human skin

Background and objectives  Fractional photothermolysis produces micro-islands of thermal injury to the skin while preserving areas among treated tissue sites in order to promote wound healing. Histological changes associated with single and multiple passes of the 1540-nm Er:Glass fractional laser were examined using in vivo human skin.
Methods and materials  Panni of five abdominoplasty patients were treated intraoperatively with a Fractional Lux1540 erbium glass laser system at various laser parameters, with single and multiple passes. Biopsies were removed and examined using standard histological stains.
Results  Deep coagulated columns of collagen separated by regions of unaffected tissue were observed at variable fluence parameters. A direct correlation between the depth of penetration of the coagulated microcolumns and increasing energies was observed. Micro-islands of coagulation were ∼250 μm in diameter and separated by ∼800 μm of unaffected tissue. With multiple passes, significantly more disruption of the dermal–epidermal junction (DEJ) occurred at higher fluences. In contrast to the controlled fractional columns observed with single-pass treatments, nonuniform coagulated columns were distributed randomly throughout the tissue when instituting multiple passes over the same treatment region.
Conclusion  Micro-islands of thermal damage were observed at variable energy parameters. Pathological changes within the skin were clearly dependent on amount of energy and number of passes of the laser treatment. Significantly more superficial damage, accompanied by disruption of the DEJ was observed with multiple passes when compared with single pass at similar fluences. However, with multiple passes, depth of thermal injury did not increase with increasing energies but did disrupt the micro-island array observed with single-pass fractional treatments.     

Perivulvar inflammatory linear verrucous epidermal nevus (ILVEN) treated with CO2 laser

Inflammatory linear verrucous epidermal nevus (ILVEN) is a type of epidermal nevus with the onset usually at early childhood. It is generally rather persistent with pruritus as a prominent symptom and is resistant to various treatments. We report a case of disfiguring ILVEN of the vulvar area, which was treated successfully with low fluence CO2 laser. The patient remains improved 2 years following laser therapy.