Short pulse intense pulsed light versus pulsed dye laser for the treatment of facial redness

Treating diffuse facial redness with an intense pulsed light (IPL) source usually requires multiple sessions and may not achieve complete clearance. The 595 nm pulsed dye laser (PDL) enjoys a good reputation for reducing facial redness with non-purpuric settings. The objective of this study was to compare facial redness reduction using these two devices. After establishing the lowest light dose able to achieve transient purpura for the same pulse width of 1,5 ms with each technology, right and left sides of the face were randomly assigned for each type of treatment. There were two treatment sessions 4 weeks apart and the final evaluation was performed 8 weeks after thesecond treatment. Four blinded experienced dermatologists analyzed pre and post-treatment photographs, which demonstrated an average of 60% improvement on the segment treated with the IPL as opposed to 45% on the other segment. Pain level was described as mild and the procedure was well tolerated for both types of treatment. In this study we showed that short-pulsed intense pulsed light and PDL are similar in decreasing facial redness when non-purpuric low fluence settings are used. The IPL was faster and did not have consumables.

One-pass CO2 versus multiple-pass Er:YAG laser resurfacing in the treatment of rhytides: a comparison side-by-side study of pulsed CO2 and Er:YAG lasers

BACKGROUND

The CO2 laser is normally described as an aggressive resurfacing tool, whereas the erbium:YAG laser has enjoyed a reputation as the ideal tool for superficial resurfacing. The implication from many studies is that the CO2 laser is incapable of "minimally invasive" resurfacing.

OBJECTIVE

To compare a short-pulsed CO2 laser with an Er:YAG laser over a range of parameters intended to produce equivalent microscopic and clinical injuries.

METHODS

A prospective, randomized, comparative interventional trial was conducted in a tertiary care teaching hospital. Thirteen patients with facial wrinkles were enrolled in the study. A side-by-side comparison was performed using periorbital and perioral regions as treatment sites. One side was treated with a pulsed CO2 laser and the other with an Er:YAG laser. Postauricular skin was treated in an identical fashion to the study sites and biopsied for microscopic analysis. The biopsies were obtained before treatment, immediately after treatment, and either 3 or 6 months after treatment to evaluate the acute level of injury and subsequent degree of fibroplasia. Photographs were taken at baseline, immediately after treatment, 1, 2, and 6 weeks, and 3 and 6 months after treatment. Nine physicians evaluated the photographs for erythema, pigmentation, and wrinkle improvement.

RESULTS

Investigator assessment showed no statistically significant differences between the lasers with respect to hyperpigmentation and wrinkle reduction. There was less erythema at the CO2 laser-treated sites 2 weeks after treatment; the differences had resolved by 6 weeks after treatment. Histologic examination demonstrated equivalent dermal thermal injury on immediate postoperative biopsies and equivalent fibroplasia on subsequent biopsies. Both CO2 and Er:YAG laser-treated sites showed overall modest wrinkle improvement compared to the pretreatment photographs.

CONCLUSION

When CO2 and Er:YAG lasers are used in a manner such that there are equivalent immediate postoperative histologic results, equivalent healing and cosmetic improvement occurs. One can use CO2 laser with one pass to mimic a moderately aggressive Er:YAG laser treatment.

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.

Tattoo darkening and nonresponse after laser treatment: a possible role for titanium dioxide

OBJECTIVE

To examine relationships between chemical composition, biopsy findings, and clinical outcome in laser-treated tattoos.

DESIGN

Observational nonblinded retrospective study.

SETTINGS

University-based dermatology clinic and private practice.

PARTICIPANTS

Twenty patients who underwent biopsy of laser-treated tattoos.

MAIN OUTCOME MEASURES

Biopsy specimens were analyzed after laser treatment, and the depths of changed particles were recorded. Ultrastructure of the changed particles was examined by electron microscopy. Presence of inorganic chemicals was determined by x-ray diffraction. Correlation between x-ray diffraction, microscopy, and clinical response was attempted.

RESULTS

Of the 20 tattoos, 7 lightened, 9 failed to change, and 4 darkened after laser treatment. There was a significant association between presence of titanium dioxide and poor response to laser therapy. Microscopic studies showed variable changes in the ink particles, but there was a trend toward residual deep green pigment in the resistant tattoos. Also, round dark stippling was observed superficially in the darkened specimens.

CONCLUSIONS

Titanium is overrepresented in tattoos that respond poorly to laser treatment. Further studies are necessary to show whether this metal is the primary cause of this poor response.

Effects of overlap and pass number in CO2 laser skin resurfacing: a study of residual thermal damage, cell death, and wound healing

BACKGROUND

Newer CO2 laser systems incorporating short pulse and scanning technology have been used effectively to resurface the skin. As the number of resurfacing cases has increased, hypertrophic scarring has been reported more commonly. Previous dermabrasion and continuous wave CO2 studies have suggested that depth of injury and thermal damage are important predictors of scarring for a given anatomic region. To determine whether rapid overlapping of laser pulses/scans significantly altered wound healing, we examined residual thermal damage, cell death, and histologic and clinical wound healing in a farm pig.

METHODS AND MATERIALS

Two popular CO2 systems were used, with a range of radiant exposures, degrees of overlap, and numbers of passes. Thermal damage was assessed by histology, and dermal cell viability was measured with nitrotetrazolium blue staining. Presence or absence of clinical scarring was determined by textural change and loss of skin markings.

RESULTS

We observed that dermal thermal damage did not increase significantly with pass number when performed as in the normal clinical setting (for 2-4 passes); however, by delivering rapidly overlapping pulses and scans, residual thermal damage and cell death depth were increased as much as 100% over areas without immediate overlap of laser impacts.

CONCLUSIONS

Immediate overlapping of CO2 laser pulses and scans is a significant risk factor in increasing thermal damage, cell death, and possibly scarring.

Effects of heterogeneous absorption of laser radiation in biotissue ablation: characterization of ablation of fat with a pulsed CO2 laser

BACKGROUND AND OBJECTIVE

Physicians encounter several clinical situations in which fat must be removed. In this study, the characterization of fat ablation produced by a pulsed CO2 laser is reported.

STUDY DESIGN/MATERIALS AND METHODS

An RF excited 800 microns pulsed CO2 laser operating at 10.6 microns was used to ablate fresh porcine fat. The heat of ablation and ablation threshold were determined using a mass loss technique. Absorption coefficients for fat and dermis were determined by attenuated total reflection spectroscopy.

RESULTS

Threshold radiant exposure and heat of ablation for fat were calculated from the mass loss measurements to be 1.05 J/cm2 and 2.4 J/cm3, respectively. The absorption coefficients of fat and dermis at 10.6 microns were 250 and 780 cm-1, respectively. Pulsed CO2 laser ablation of fat caused ejection of fat droplets, which ignited after high fluence pulses.

CONCLUSION

A pulsed CO2 laser can effectively ablate fat with a threshold fluence and efficiency comparable to other soft tissues. Our data suggest that fat ablation occurs primarily through the ejection of intact fat particles via the explosive vaporization of intervening water "lakes".

Nonablative skin remodeling: selective dermal heating with a mid-infrared laser and contact cooling combination

BACKGROUND AND OBJECTIVE

Many of the microscopic changes associated with photodamage reside in the dermis. It follows that subsurface heating of the skin might allow for cosmetic enhancement without loss of the epidermis. Accordingly, we investigated the clinical and microscopic changes produced by a mid-infrared laser coupled with a contact cooling device.

STUDY DESIGN/MATERIALS AND METHODS

Nine patients were treated with an erbium glass laser and sapphire cooling handpiece in contact with the skin. Postauricular sites were irradiated with pulse energies varying from 400-1,200 mJ and numbers of pulses from 4 to 40. Outcome measures included pain, edema, and erythema at predetermined postoperative intervals. Biopsies were performed just after treatment and 2 months postoperatively for selected pulse energy-pulse number combinations.

RESULTS

Erythema, edema, and pain increased with pulse energy and number of pulses. Likewise, immediate epidermal necrosis and subsequent scarring were observed for larger pulse energy-pulse number combinations. At sites with epidermal preservation, on biopsy, immediate dermal thermal damage was observed in a band-like pattern. The deep boundaries of this band were dependent on pulse energy and pulse number. After 8 weeks, biopsies showed dermal fibroplasia roughly correlating to the band of immediate dermal thermal damage.

CONCLUSION

Selective dermal heating can be achieved with a mid-infrared laser coupled to a contact surface cooling device. In this study, the range of fibroplasia and lack of clinically substantial cosmetic enhancement suggest that the dermal thermal damage achieved may be too deep and that the injury should be confined to more superficial levels to alter the most severely photodamaged dermis. Lasers Surg. Med. 26:186-195, 2000. Published 2000 Wiley-Liss, Inc.

Skin disorders in amputees

BACKGROUND

Dermatologic problems restrict the normal use of a prosthetic limb. The importance of contact dermatitis to skin morbidity in a population of amputees and the selection criteria for patch testing have not been clearly defined.

OBJECTIVE

We describe the range of dermatoses seen in a population of amputees and examine the incidence, causes, and patterns of contact dermatitis.

METHODS

This is a questionnaire-based, cross-sectional study of 210 amputees. Those with a skin problem were assessed by a dermatologist. Patch testing was undertaken in patients with persistent dermatitis.

RESULTS

A total of 34% of amputees experienced a skin problem. Lesions resulting from friction, pressure, and occlusion are common. Allergic contact dermatitis is seen in a third of patients with stump dermatitis. There are no features that distinguish allergic from irritant (chemical or physical) dermatitis.

CONCLUSION

Dermatologic problems are common in prosthetic limb users. Allergic contact dermatitis is a significant problem, and all patients with dermatitis on the residual limb should be patch tested.

Comparison of carbon dioxide laser, erbium:YAG laser, dermabrasion, and dermatome: a study of thermal damage, wound contraction, and wound healing in a live pig model: implications for skin resurfacing

BACKGROUND

Advances in laser technology allow for precise tissue removal and minimal thermal damage. However, mechanisms for cosmetic improvement have not been determined. Investigators have suggested that ablation, collagen shrinkage, and new collagen deposition all contribute to the clinical outcome.

OBJECTIVE

In a live farm pig, we examined gross and microscopic effects of thermal and mechanical ablation devices to characterize immediate and long-term mechanisms in skin rejuvenation.

METHODS

Two CO(2) lasers, an erbium:YAG laser, a dermabrader, and a dermatome were used to treat flank skin in a farm pig. There were 14 different treatment groups based on device type and working parameters. One to five sites were treated for each group. Wound surface areas were measured before treatment, immediately after treatment, and 7, 17, 23, 30, and 60 days thereafter. Biopsies were performed immediately after irradiation and 2, 7, 17, and 60 days after treatment.

RESULTS

For the CO(2) laser-induced wounds, surface area measurements showed that immediate and final wound contraction tended to increase with initial residual thermal damage (RTD) for a range of values, above which immediate contraction remained relatively constant. Although there was no immediate wound contraction with mechanical ablation devices, long-term wound contraction in the dermatome and dermabrasion sites increased with depth of ablation. The erbium:YAG laser sites healed in a manner similar to that of mechanically induced wounds. Wound contraction profiles over time were dependent on depth of RTD and depth of ablation. Sixty days postoperatively, histologic examination showed varying degrees of fibroplasia. Overall, there was greater compaction and horizontal orientation of collagen fibers in those wounds with more than 70 microm of dermal RTD. Grossly, all wounds were similar after 60 days, with the exception of the deep dermabrasion sites, at which clinical scarring was observed.

CONCLUSION

Our results show that CO(2) laser resurfacing produces short- and long-term wound contraction that is greater than that induced by purely ablative methods for the same total depth of injury. The erbium laser produced wound contraction profiles similar to those produced by mechanical wounding. The data suggest that initial collagen contraction and thermal damage modulate wound healing.

A pilot study of in vivo immediate tissue contraction with CO2 skin laser resurfacing in a live farm pig

BACKGROUND

It has been suggested that tissue ablation, collagen shrinkage, and new collagen deposition contribute to the clinical outcome of laser skin resurfacing.

OBJECTIVE

To study the effects of fluence and pass number on thermal damage and tissue shrinkage, we performed experiments in an in vivo farm pig model.

METHODS

A CO2 laser was used to treat the flank skin of a farm pig. There were nine treatment sites based on number of passes and fluence per pass. Wound surface areas were measured pretreatment and immediately posttreatment. Biopsies were performed immediately after irradiation.

RESULTS

Surface area measurements showed that immediate contraction tended to increase with increasing fluence and pass number up to a maximum of approximately 38% shrinkage, after which the percent contraction remained constant. Thermal damage increased with pass number for low and moderate fluence groups; however, in high fluence groups the thermal damage remained constant with an increasing number of passes.

CONCLUSIONS

Our results suggest that CO2 laser resurfacing produces immediate tissue contraction and residual thermal damage that is saturable for multiple passes and high fluences. For small fluences, however, there is an almost linear increase in thermal damage and shrinkage with an increasing number of passes.

Why does carbon dioxide resurfacing work? A review

Despite the unquestionable efficacy of carbon dioxide laser skin resurfacing, mechanisms for cosmetic enhancement remain poorly characterized. Histological studies have provided some insight into the cascade of events from initial laser impact to final skin rejuvenation. However, there are few comprehensive studies of gross and microscopic wound healing. Additionally, the literature is fragmented; excellent individual articles appear in journals from widely disparate disciplines. For example, some reports relevant to laser skin resurfacing are "sequestered" in the engineering literature. This article is intended to update the physician on laser skin resurfacing based on the broadest review of the current literature. It proceeds from a discussion of initial laser-tissue interactions, such as collagen denaturation, to examination of long-term biological sequelae. At some cost to scientific rigor, mathematical models describing laser-tissue interactions are not presented.

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.

The clinical superiority of continuous exposure versus short-pulsed carbon dioxide laser exposures for the treatment of pearly penile papules

Treatment of pearly penile papules was performed both with a conventional continuous-wave (CW) and a newer generation high energy pulsed carbon dioxide laser. When compared to the short pulsed laser, the CW laser, using relatively low power densities, provided superior hemostasis and improved visualization of the operative field. Despite the increase in thermal injury, wound healing was not compromised. The results of this case report support the CO2 laser in CW mode as the infrared laser treatment of choice for exophytic lesions with increased vascularity.

The effect of wiping on skin resurfacing in a pig model using a high energy pulsed CO2 laser system

BACKGROUND

The impact of wiping in laser skin resurfacing has not been systematically studied.

METHODS

We examined the effects of wiping during single- and multiple-pass high energy pulsed CO2 laser skin resurfacing in a farm pig. Consequences of wiping were evaluated with regard to depth of residual thermal damage, tissue necrosis, and fibroplasia. Also, the impact of wiping on gross wound healing was observed. Wounds were followed for 21 days and biopsies were obtained on postoperative days 0, 1, and 21.

RESULTS

Immediate postoperative biopsies of single-pass wounds showed equivalent residual thermal damage regardless of wiping; in contrast, biopsies from multiple-pass sites without wiping showed more extensive and variable residual thermal damage than wiped sites. On postoperative day one, single pass sites without wiping were grossly less erythematous than wiped sites, and biopsies showed less extensive necrosis and inflammation. In contrast, multiple pass sites without wiping were grossly more erythematous than corresponding wiped sites, and biopsies revealed significantly increased and variable necrosis. After 21 days, multiple pass sites without wiping were grossly more erythematous and showed a thicker band of fibroplasia microscopy.

CONCLUSIONS

For single pass wounds, not wiping decreased the level of wounding. In contrast, not wiping in multiple pass wounds significantly increased the depth and variability of residual thermal damage and necrosis, resulting in prolonged healing.

Lasers in the military for cutaneous disease and wound healing

The clinical laser experience of military dermatologists mirrors that of their civilian counterparts; however, there are applications for lasers in dermatology in which there is special military relevance. These range from treatment of common diseases such as pseudofolliculitis barbae to noninvasive identification of shrapnel injuries on the battlefield using novel laser-based diagnostic techniques. Although some applications in this report are experimental, emerging technologies should allow for their clinical or field implementation in the near future.

The use of the 1.0 mm handpiece in high energy, pulsed CO2 laser destruction of facial adnexal tumors

BACKGROUND

The treatment of syringoma and trichoepithelioma has included punch and shave biopsy, excision, electrodessication, as well as continuous wave and superpulsed carbon dioxide laser ablation. More recently, high-energy pulsed CO2 lasers have been reported to be effective with standard available handpieces that deliver collimated beams.

OBJECTIVE

To report our experience using a focusing handpiece (1.0 mm spot at focus) with a high energy pulsed CO2 laser.

METHODS

Four patients with syringoma and two with multiple trichoepithelioma were treated with a high energy pulsed CO2 laser using a 1 mm spot size focusing handpiece. Pulse energies ranged from 125 to 250 mJ. All patients were followed 2 weeks after treatment and then for variable periods ranging from 8 to 18 months (mean=13.3 months).

RESULTS

The 1 mm spot focusing handpiece permitted rapid tumor ablation with optimal matching of lesion size and laser spot diameter. Recurrence of tumor was associated with superficial ablation while complications such as hypopigmentation and atrophy were associated with deeper ablation.

CONCLUSION

Facial adnexal tumors such as syringoma and trichoepithelioma can be successfully treated with the 1.0 mm handpiece in tandem with high energy pulsed CO2 lasers.

Incidence of postoperative infection or positive culture after facial laser resurfacing: a pilot study, a case report, and a proposal for a rational approach to antibiotic prophylaxis

BACKGROUND

Laser skin resurfacing (LSR) has emerged as a popular procedure for facial rejuvenation; however, there are no clear guidelines regarding systemic antibiotic prophylaxis.

OBJECTIVE

We attempt to provide practical guidelines for antibiotic prophylaxis in LSR based on our experiences, pharmacology, and a review of the literature.

METHODS

In a pilot study, four consecutive full-face LSR patients were treated without oral or topical antibiotics. The next four patients received oral prophylaxis with a narrow spectrum antibiotic. We also report the case of a severe gram-negative infection after LSR.

RESULTS

For full-face LSR, 2 of 4 consecutive patients without antibiotic prophylaxis experienced focal Staphylococcus aureus infection. The next 4 consecutive patients, who had received gram-positive oral prophylaxis, were all culture negative after 2 days. All test sites (5 of 5) were culture negative despite the absence of systemic or topical antibiotics. One patient not in the pilot study receiving gram-positive antibiotic prophylaxis experienced a gram-negative infection.

CONCLUSION

We recommend narrow-spectrum gram-positive oral antibiotic coverage for full-face and regional LSR.

Protoporphyrin IX fluorescence induced in basal cell carcinoma by oral delta-aminolevulinic acid

Limited depth of penetration significantly limits photodynamic therapy of nodular basal cell carcinoma (BCC) using topical delta (5)-aminolevulinic acid (ALA). To demonstrate safety and efficacy of orally administered ALA in inducing endogenous protoporphyrin IX (PpIX) production in BCC, 13 patients with BCC ingested ALA in a dose-escalation protocol. All dose ranges (10, 20 or 40 mg/kg single doses) resulted in formation of PpIX in human skin and BCC, measurable by in vivo fluorescence spectrophotometry. The PpIX fluorescence peaked in tumors before normal adjacent skin from 1 to 3 h after ALA ingestion. Gross fluorescence imaging of ex vivo specimens revealed greater PpIX fluorescence in tumor than normal skin only at the 40 mg/kg dose. Fluorescence microscopy confirmed this finding by showing distinct, full-thickness PpIX fluorescence in all subtypes of BCC only after ALA given at 40 mg/kg. Side effects were dose dependent and self limited. Photosensitivity lasting less than 24 h and nausea coinciding with peak skin PpIX fluorescence occurred at 20 and 40 mg/kg doses. After 40 mg/kg ALA, serum hepatic enzyme levels rose to a maximum within 24 h, then resolved over 1-3 weeks. Transient bilirubinuria occurred in two patients.

Protoporphyrin IX fluorescence induced in basal cell carcinoma by oral delta-aminolevulinic acid

Limited depth of penetration significantly limits photodynamic therapy of nodular basal cell carcinoma (BCC) using topical delta (5)-aminolevulinic acid (ALA). To demonstrate safety and efficacy of orally administered ALA in inducing endogenous protoporphyrin IX (PpIX) production in BCC, 13 patients with BCC ingested ALA in a dose-escalation protocol. All dose ranges (10, 20 or 40 mg/kg single doses) resulted in formation of PpIX in human skin and BCC, measurable by in vivo fluorescence spectrophotometry. The PpIX fluorescence peaked in tumors before normal adjacent skin from 1 to 3 h after ALA ingestion. Gross fluorescence imaging of ex vivo specimens revealed greater PpIX fluorescence in tumor than normal skin only at the 40 mg/kg dose. Fluorescence microscopy confirmed this finding by showing distinct, full-thickness PpIX fluorescence in all subtypes of BCC only after ALA given at 40 mg/kg. Side effects were dose dependent and self limited. Photosensitivity lasting less than 24 h and nausea coinciding with peak skin PpIX fluorescence occurred at 20 and 40 mg/kg doses. After 40 mg/kg ALA, serum hepatic enzyme levels rose to a maximum within 24 h, then resolved over 1-3 weeks. Transient bilirubinuria occurred in two patients.

Long-term results after CO2 laser skin resurfacing: a comparison of scanned and pulsed systems

BACKGROUND

New laser technology permits the use of high-energy pulsed and continuous-wave carbon dioxide (CO2) lasers with flashscanners to treat rhytides.

OBJECTIVE

We compared the efficacy and side effects of the two leading CO2 lasers used in skin resurfacing.

METHODS

A total of 28 patients with facial rhytides were treated with either the UltraPulse or SilkTouch laser systems; in five additional patients, contralateral cosmetic units were treated with one system or the other in a direct comparison of the lasers.

RESULTS

We compared photographs taken before and after treatment, and a lessening of facial wrinkling was noted in all subjects. In some subjects improvement was confirmed by optical profilometry methods. Biopsy specimens in representative patients showed that immediate thermal damage was limited to 180 microns. Long-term postoperative specimens showed changes in the papillary dermis consistent with new collagen deposition and reduction of pretreatment solar elastosis. Posttreatment facial erythema was noted in half the patients for up to 2 months; transient hyperpigmentation was observed in one third of the treated areas.

CONCLUSION

Although the SilkTouch system produced more immediate thermal damage, there were no significant differences in efficacy or adverse effects between the lasers. Our results suggest that both laser systems, used with appropriate settings, are capable of safely smoothing the skin surface.

Selectivity of protoporphyrin IX fluorescence for condylomata after topical application of 5-aminolaevulinic acid: implications for photodynamic treatment

To examine the potential of using photodynamic therapy (PDT) in condylomata, we studied the distribution and kinetics of protoporphyrin IX (PpIX) formation in condylomata acuminata and adjacent normal skin after topical application of 5-aminolaevulinic acid (ALA). PpIX fluorescence spectra were measured hourly in vivo after ALA application. After gross fluorescence imaging, the lesions were biopsied, and fluorescence microscopy was performed. All three PpIX fluorescence detection modalities suggested selectivity of PpIX formation in condylomata after topical ALA application. In 17 of 25 condylomata, there was significantly greater fluorescence compared with adjacent normal skin. The greatest lesional to normal skin fluorescence ratios occurred after 2 h. The most likely mechanism for increased lesional PpIX formation in condylomata is enhanced stratum corneum permeability. Based on our results, ALA/PDT is a potential field therapy for condylomata. PpIX fluorescence imaging after ALA application may also be useful for localizing condylomata prior to treatment.

Effects of CO2 laser pulse duration in ablation and residual thermal damage: implications for skin resurfacing

BACKGROUND AND OBJECTIVES

Resurfacing with the CO2 laser is rapidly gaining acceptance for skin rejuvenation. Advances in CO2 laser and scanning technology allow for precise tissue removal with minimal thermal damage. High energy CO2 laser pulses have been widely used effectively to smooth the surface of facial skin; however, pulse duration effects on ablation and thermal damage have not been systematically studied over the milli-second region (0.25-10 ms).

STUDY DESIGN/MATERIALS AND METHODS

This study characterizes the ablation threshold, heat of ablation, and residual thermal damage in skin resulting from CO2 laser pulses with a Gaussian beam profile. Mass loss from fresh pig skin was measured with an analytical balance, and residual thermal damage was determined through histology.

RESULTS

Pulse durations > 1 ms were associated with higher ablation thresholds and localized increased thermal damage.

CONCLUSIONS

Our results show that although pulse duration is an important determinant in ablation and thermal damage, irradiance is more critical as an independent parameter in predicting the effects of CO2 laser pulses.

Pseudofolliculitis barbae associated with an unusual hair whorl

Descriptions of hair direction in the literature have emphasized unusual patterns of the scalp and associated developmental brain defects. We present the case of a white patient with unilateral pseudofolliculitis barbae associated with a hair whorl in the inframandibular region. To our knowledge, this is the first reported case of pseudofolliculitis barbae associated with a hair whorl.

Xanthomatized atypical T cells in a patient with mycosis fungoides and hyperlipidemia

BACKGROUND

Lipoprotein-T-cell interactions are being reported with increasing frequency, and there is evidence that lipoproteins play a role in immunoregulation. We describe a patient with mycosis fungoides and hyperlipidemia who developed xanthomatization in one preexisting plaque. The case is unique in that some of the lipidized cells were atypical T cells. In previously reported cases of mycosis fungoides with dystrophic xanthomatosis, the lipid-containing cells have been identified only as histiocytes.

OBSERVATIONS

Immunopathologic features, electron microscopy, and lipid stains of the xanthomatized plaque demonstrated that some of the lipid-laden cells were atypical T cells.

CONCLUSIONS

In mycosis fungoides, malignant T cells may be intimately involved in processing of tissue lipids. We suggest that low-density lipoprotein receptors on activated T cells facilitated the cytoplasmic lipidization in this case.

Widespread Candida folliculitis in a nontoxic patient

We present a case of widespread Candida folliculitis in a nontoxic, immunocompetent woman. Predisposing factors included obesity and use of systemic antibiotics and topical steroids. Diagnosis was made through potassium hydroxide and Gram's stain examination of the pustular contents. The patient was treated with oral ketoconazole and topical econazole, with resolution of the eruption in six weeks. We suggest that temperature played a role in the follicular location of the lesions.

Pseudomonas toe web infections

We present the case of a patient with a presumed tinea pedis infection who was referred to us after being treated with oral griseofulvin for two weeks with no improvement. We used a simple Wood's light examination and culture to establish the diagnosis of Pseudomonas toe web infection and achieved rapid resolution with oral ciprofloxacin treatment and local application of Castellani's paint.

Ichthyosiform scaling secondary to megavoltage radiotherapy

Acquired ichthyosis is a rare dermatosis associated with a number of malignancies. Side effects seen on the skin secondary to megavoltage radiotherapy are uncommon but may include fine dry desquamation and tanning. We present a case of ichthyosiform scaling limited to the radiation fields in a patient treated for brain metastases of a primary small cell lung carcinoma. The reader is reminded that side effects of megavoltage treatment do occur on the skin. A brief review of these effects is included.

Measurement of impotence by laser Doppler flowmetry and conventional methodology

The problem of vasculogenic impotence was evaluated by laser Doppler flowmetry with the LD5000 capillary perfusion monitor to determine cutaneous penile blood flow in 25 men defined previously as impotent by Doppler ultrasound with penile brachial ratios of 0.63 +/- 0.14. Erotic visual stimulation for 1, 2 and 4 minutes did not statistically change the cutaneous flow as measured by laser Doppler flowmetry from its baseline of 20 mv. The dynamics of skin microcirculation in the penis may reflect changes in the deeper vessels and represent an alternate, dependable method to evaluate capillary perfusion.

Meat tenderizer in the acute treatment of imported fire ant stings

Meat tenderizer containing the proteolytic enzyme papain was tested for therapeutic efficacy in the sting of the imported fire ant. The parameters of pain and itching were used to evaluate qualitatively the sting response in 22 healthy medical students, and the laser Doppler velocimeter was used to assess quantitatively the change in cutaneous blood flow. The results indicated that, during the acute-phase reaction, no clinically or statistically significant difference was found between stings treated with meat tenderizer and stings treated without tenderizer. Therefore we conclude that meat tenderizer is of no therapeutic value in the acute treatment of the imported fire ant sting.