CO2 Laser Resurfacing of PsoriaticPlaques: A Pilot Study

Maria Beatrice T. Alora, MD, R. Rox Anderson, MD, Timothy R. Quinn, MD, CM,and Charles R. Taylor, MD*

Department of Dermatology, Harvard Medical School, Wellman Laboratories ofPhotomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114

Background and Objective: Laser resurfacing can precisely re-move epidermis and papillary dermis, sites pivotal to the patho-genesis of psoriasis. Our objective was to determine the efficacyand safety of superficially ablating carbon dioxide (CO2) lasersfor treating isolated, recalcitrant psoriatic plaques.Materials and Methods: Twelve adult subjects with stable,plaque-type psoriasis were recruited. In six volunteers, thequadrants received different numbers of passes with a 60 msecpulsed CO2 (Tru-Pulse) laser. In the remaining patients, onequadrant underwent curettage prior to resurfacing, the secondresurfacing with a scanned continuous wave (Sharplan Silk-touch) CO2 laser and the last curettage alone.Results: Despite clinical and histological evidence of completeablation of the epidermis and papillary dermis, most quadrantsrecurred within 8 weeks. Surprisingly, two patients showed norecurrence after 4 months.Conclusion: Ablation of the entire epidermis and papillary der-mis with either pulsed or scanned CO2 lasers appears generallyineffective in treating recalcitrant psoriatic plaques, althoughthe clearing seen in two patients suggests potentially successfulfuture research directions. Lasers Surg. Med. 22:165–170, 1998.© 1998 Wiley-Liss, Inc.

Key words: CO2; resurfacing; psoriasis

INTRODUCTION

Psoriasis is a common dermatologic diseasecharacterized by hyperproliferation of the epider-mis and affecting 1–2% of the world’s population.The exact cause(s) remain unknown, although ab-normal keratinocyte differentiation, polymorpho-nuclear leukocytes, neuropeptides, arachidonicmetabolites, complement and immunologicmechanisms have all been reported to be in-volved. The earliest observable changes in psori-atic skin seen even prior to the development of aclinically apparent plaque are visible in the der-mal papillary vasculature [1]. These events maybe responsible for the initiation and perpetuationof typical plaques. There is apparently no reliableanimal model for psoriasis. At present, psoriasisis treatable but not curable. Treatment optionssuch as topical steroids, vitamin D derivatives,immunosuppressives, ultraviolet light therapy,

and retinoids provide temporary benefit. Someplaques, however, remain recalcitrant to all formsof therapy. Such stubborn lesions are often on theelbows, knees, buttocks, and sacrum. These resis-tant areas are a source of continued frustration toboth patient and physician.

Although lasers have not been traditionallyemployed for treating dermatoses, there is someprecedent for considering their therapeutic use inpsoriasis. First, the pulsed dye laser has beenshown to induce prolonged remission in chronicplaque psoriasis [2,3]. Two early studies with the

Contract grant sponsor: Palomar Medical Technologies.

*Correspondence to: Charles R. Taylor, MD, Department ofDermatology, Wang ACC, 477, Massachusetts General Hos-pital, Boston, MA 02114.

Accepted 18 November 1997

Lasers in Surgery and Medicine 22:165–170 (1998)

© 1998 Wiley-Liss, Inc.

continuous wave (CW) carbon dioxide (CO2) laserhave shown promise [4,5]. The skin was preciselydestroyed to a depth of 1 mm in three cases ofcircumscribed plaque psoriasis using a CO2 laserwith power density of 160–200 watts/cm2 and aspot size of 2 mm. These reports challenge thewidely accepted phenomenon of Koebnerizationfollowing trauma of psoriatic skin. One proposedhypothesis suggests that destruction of the super-ficial dermal microvasculature may remove a piv-otal element in the pathogenesis of psoriasis. An-other possible mechanism involves the destruc-tion of fibroblasts in the upper dermis, which areknown to induce hyperproliferation of normal ke-ratinocytes [6]. Finally, severance of cutaneousnerve endings, a source of neuropeptides [7] thatmay provoke psoriasis, has been proposed to bethe mechanism.

Given costs, risks of infection, and time con-straints, it seems unlikely that anyone would se-riously suggest treating large body surfaces withCO2 lasers at this time. However, new CO2 lasersfor ‘‘resurfacing’’ skin might conceivably be usedeffectively and permanently to ablate isolatedpsoriatic plaques, especially those lesions in diffi-cult to treat areas or those refractory to less ag-gressive modalities. The objective of this studywas to determine the efficacy and safety of twosuperficially ablating carbon dioxide lasers fortreatment of isolated, recalcitrant plaques. We ex-amined the effect of the number of laser ‘‘passes,’’the anatomic depth of tissue ablation, and com-pared this laser technique to curettage.

MATERIALS AND METHODS

Informed consent was obtained from all vol-unteers who were recruited. Twelve nonpregnant,nonlactating adult volunteers with stable psoria-sis having at least one plaque measuring a mini-mum of 20 cm2 were recruited. Stable was definedas being present and unchanged for at least 3months. Subjects were excluded if they had beenon any systemic therapy such as oral steroids,methotrexate, cyclosporine, etretinate, hydroxy-urea, and sulfasalazine within the past 8 weeks.Also excluded were those who had received UVBor PUVA phototherapy within the past 4 weeks orthose who had used topical treatments such assteroids, calcipotriol, tar, and anthralin withinthe past 2 weeks. Those with a known history ofkeloids or hypertrophic scar formation were alsoexcluded. Finally, patients on known photosensi-tizing medications were also excluded.

The test plaque was assessed according toerythema, thickness, and scaling. Each individualparameter was graded according to the samescale as follows: absent, slight, moderate, severe,and very severe. The volunteers were sequentiallyassigned to one of two groups, as described below.

Treatment Group A: Varying Depth of Pulsed CO 2

Laser Ablation

In this group, the selected test plaque wasdivided into equal quadrants. After sterile prepa-ration, 1% lidocaine with epinephrine was infil-trated intradermally into the entire plaque. Onequadrant was left untreated and served as a con-trol. The remaining quadrants received increas-ing numbers of passes ranging from 2 to 22 withthe pulsed Tru-Pulse CO2 laser (Palomar MedicalTechnologies, Beverly, MA) at a pulse energy of500 mJ and a spot size of 3 mm. This laser causessuperficial ablation at this pulse energy. Debride-ment was performed after each pass using saline-soaked gauze. Because psoriatic plaques varied inthickness, resurfacing and debridement were ini-tially performed until no more epidermis wasclinically visible in the first quadrant undergoingtreatment. In order to be certain a deep enoughlevel of the papillary dermis had been reached, anadditional 1-3 passes were performed on the nextquadrant undergoing treatment. The final treat-ment quadrant received yet another 1–3 passesbeyond those given in the intermediate quadrant.

Treatment Group B: Comparison of Pulsed CO 2

Laser With Other Destructive Modalities

In order to reduce the thickness of the pso-riatic plaques more efficiently, superficial curet-tage with a 4 mm curet was performed until theplaque was at appreciably the same height as thesurrounding epidermis. In addition, a scannedcontinuous wave (c.w.) CO2 laser, (Sharplan Silk-touch, Sharplan Lasers, Allendale, NJ) was em-ployed on one of the quadrants. This scanned c.w.laser achieves higher energies and causes greaterthermal damage, potentially reducing the needfor curettage and multiple passes.

As in the first group, the test plaque wasdivided into quadrants, sterilely prepared and in-filtrated with 1% lidocaine with epinephrine. Thefirst quadrant served as a control. The secondquadrant underwent curettage until no epidermiswas visible, then laser resurfacing with the Tru-Pulse CO2 laser using a pulse energy of 500 mJwith a spot size of 3 mm. The third quadrant wastreated with the Sharplan Silktouch CO2 laser us-

166 Alora et al.

ing a laser power of 16 W, with 0.2 sec on/0.4 secoff exposure cycle and a scanned spot size of 6 mmper exposure cycle. This laser scanner employs acontinuously spiraling mechanism that achievessomewhat the effect of a pulsed laser. Resurfacingwas performed on the second and third quadrantsuntil tissue contraction was seen. Debridementwas performed after each pass with wet saline-soaked sponges. The fourth quadrant was treatedwith curettage alone.

Biopsies

Punch biopsies (4 mm) were performed onwilling subjects before and immediately after la-ser resurfacing to facilitate ablation and coagula-tion necrosis depth assessment. The specimenswere fixed in 10% buffered formalin and routinelystained with hematoxylin and eosin.

Postlaser Care and Evaluation

All subjects were asked to clean the areaswith mild liquid soap and apply bacitracin oint-ment twice daily under a Telfa nonstick dressingfor 1 week. Clinical evaluation and photographywere performed within 1 week of treatment andagain at 2, 4, and 8 weeks.

RESULTS

Treatment Group A

All six patients in group A completed the pro-tocol. There were five men and one woman with amean age of 42 years (range 23–61 years). Fitz-patrick [8] skin type distribution, the location oftheir test plaques, and the number of passes per-formed are listed in Table 1. There was no differ-ence in response between quadrants that receivedvarying numbers of passes. In five of the six pa-

tients, recurrence of the entire plaque was seenwithin 8 weeks of resurfacing. In the remainingpatient, a reduction in thickness and scaling wasnoted at 4 weeks in all treated areas; however, theentire plaque returned to baseline by 12 weeks.

Treatment Group B

All six patients in group B also completedthis protocol. There were five men and one womanwith a mean age of 45 (range 18–61 years). Thefirst four patients showed complete recurrence inall treated quadrants, starting as soon as 2 weeksafter the treatment and returning to baseline sta-tus by 8 weeks (Table 2). The last two subjects,however, showed no recurrence in the second andthird quadrants 4 months after laser resurfacing.These subjects received the greatest number ofpasses.

No adverse effects were noted in either sub-group. There were no wound infections. All sub-jects tolerated the treatments extremely well.Neither permanent pigmentary, nor textural ef-fects, nor scarring were noted in any subject.

Biopsies

Thirteen specimens were obtained for stan-dard hematoxylin and eosin sections. Controlplaques showed the morphologic features typicalof fully developed lesions of psoriasis, namely,regular psoriasiform epidermal hyperplasia,marked parakeratosis, subjacent attenuation orabsence of granular cell layer, thinning of the su-prapapillary epidermis, and an increased basilarmitotic index. Variable features included collec-tions of neutrophils (Munro microabscess), dilatedtortuous vessels with an edematous papillary der-

TABLE I. Treatment Group A. Varying Numbers of Tru-Pulse CO2 Passes

Patientdata

Skintype Site Scale Erythema Thickness No. of passes Results*

RH 43/M II L flank Severe Moderate Moderate 2–4–6 2 wks—back to baselineLB 43/F II R knee Minimal Moderate Thin 2–4–6 2 wks—recurrenceIG 61/M III R thigh Severe Moderate Severe 6–8–10 2 wks—thin plaques;

4 wks—back to baselineCA 23/M II R leg Moderate Minimal Thin 2–3–4 72 hours—signs of recurrence;

8 wks—back to baselinePS 46/M III R leg Severe Moderate Moderate 16–19–22 1 wk—macular;

2 wks—thin plaques;8 wks—back to baseline

OG 36/M IV R leg Severe Moderate Thin 14–17–20 8 wks—signs of recurrence;12 wks—back to baseline

*Footnote: Regardless of the number of Tru-Pulse CO2 passes, there was no difference in response.

CO2 Resurfacing of Psoriasis 167

mis, a superficial, predominantly mononuclear in-filtrate, and papillary dermal concentric eosino-philic fibroplasia.

For group A, plaques immediately aftertreatment showed residual epidermis focally pres-ent; thickness ranged from 0.02–0.075 mm. Forgroup B, plaques immediately after treatmentshowed typical alterations observed in acute, highenergy thermal injury. No consistent differencewas observed between the Tru-Pulse laser follow-ing curettage and the Sharplan Silktouch lasertherapy alone. The epidermis was absent exceptfor a few tufts of viable keratinocytes two to threelayers thick. When present, the papillary dermiswas capped by narrow zones of basophilic homog-enized collagen fibers. In other areas, the papil-lary dermis was completely obliterated (Fig.1).Capillary endothelial injury consisted of coagula-tion necrosis of superficial endothelial cells. Sev-eral lumina contained necrotic cellular debris, co-agulated red blood cells, and fibrin.

DISCUSSION

Psoriasis is a disease that continues to per-plex physicians and torment patients around theworld. Despite recent advances in therapy, allcurrently available treatment options do not at-tain permanent cure.

Lasers are a relatively new technology thathave been tried for a wide range of dermatologicconditions including psoriasis. Indeed, differentkinds of lasers have been used for treating local-ized psoriatic plaques, most notably the flashlamppulsed dye laser [2,3], argon laser [9], and the CO2laser[4,5]. Pulsed dye lasers emit at a wavelengthof 585 nm, visible radiation that selectively de-stroys cutaneous blood vessels up to a depth of atleast 0.5 mm. Since the dermal papillary vascula-ture is believed to be responsible for the initiationand perpetuation of psoriasis, it was hoped that

destruction of this plexus would result in clearingof psoriasis. Katagampola et al. [2] achieved mod-erate success with 5 out of 8 patients showing 50%improvement on the treated areas, but only afterthree fortnightly treatments with a fluence of 8.5J/cm2 (585 nm) and a spot diameter of 5 mm. Onlyone of their patients showed complete resolution.

TABLE II. Treatment Group B. Curettage vs. Curettage Plus Tru-Pulse (T) vs. Sharplan Laser Resurfacing (S)

Patientdata

Skintype Site Scale Erythema Thickness

No. of passes(T vs. S) Results*

RH 43/M II R lowerabdomen

Moderate Minimal Thin 6–4 2 wks—signs of recurrence;8 wks—back to baseline

PS 46/M III L leg Moderate Moderate Thin 10–7 8 wks—recurrenceIG 61/M III L knee Severe Moderate Moderate 8–8 2 wks—signs of recurrence;

8 wks—back to baselinePC 18/M II R leg Moderate Moderate Thin 8–6 8 wks—back to baselineSM 42/M III R knee Severe Moderate Severe 14–12 no recurrence at 4 mosJW 52/F I L leg Moderate Severe Moderate 10–8 no recurrence at 4 mos

*Footnote: All plaques treated with curettage along recurred within 8 weeks.

Fig. 1. High-power magnification H&E histology showingcomplete obliteration of the epidermis and papillary dermisimmediately after laser treatment. Despite attaining suchdepth of ablation, recurrence of psoriatic plaque was noted.

168 Alora et al.

Zelickson et al. [3] also used the pulsed dye laserand reported remissions of up to 13 months. Dis-advantages of this modality are the need for mul-tiple treatments and the high cost compared toeffectiveness.

Harrison et al. [9] used an argon laser irra-diating at 515 nm with a power of 250 mW, tophotocoagulate plaques of psoriasis, in 19 pa-tients. During the 12 months of their study, norecurrence of psoriasis was noted. Histologically,a significant reduction in epidermal thicknesswas observed, and superficial scar formation wasseen clinically and histologically. It is not clearwhether scarring is related to the potential forclearing of laser-treated psoriasis.

For over two decades, the traditional CO2 la-ser has been used for tissue vaporization, coagu-lation, and cutting. It emits light at 10,600 nm, afar-infrared wavelength strongly absorbed by wa-ter. Unfortunately, there is a tendency to leavebehind a very wide zone of coagulation necrosis,often resulting in unacceptable degrees of scar-ring. In 1985, success in treating three patientswith circumscribed plaque psoriasis using a car-bon dioxide laser in a continuous mode was re-ported [4]. The healed areas, although slightly de-pigmented, were as soft and elastic as normalskin. Histologically, aside from the slightly al-tered pigmentation, the skin in the treated areawas normal in structure. These areas were re-ported to remain free of psoriasis for 31⁄2 years.Morselli et al. [5] also successfully treated psori-atic plaques using a similar technique.

Psoriasis involves primarily the upper layersof the skin, namely, the epidermis and papillarydermis. These are the same layers removed bysequential, superficial laser ‘‘resurfacing’’ tech-niques used for treating rhytides and acne scarson the face [10,11]. Although CO2 laser resurfac-ing causes mild fibrosis in the upper dermis, suchchanges may not be clinically apparent when thelayer of fibrosis is thin. Because skin resurfacinglasers achieve more precise tissue ablation, theymay conceivably provide an alternative treatmentfor isolated, recalcitrant plaques of psoriasis. Sev-eral different versions of CO2 laser systems havebeen used to achieve precise tissue ablation forresurfacing. Automated scanning of a focussed,CW CO2 laser also achieves superficial tissue va-porization. As used in this study, the SharplanSilktouch CO2 laser uses a rapidly scanning fo-cused laser beam. With this device, the beam isscanned in a spiral pattern so that any given spotof tissue is irradiated for ∼1 msec with an energy

density of 5–15 J/cm2 or more. Pulsed CO2 lasers,such as the Tru-Pulse device used in this study,typically ablate a layer 50–150 mm deep per passwhen used at 500 mJ energy over a 3 mm spot perpulse. An advantage of the Tru-Pulse laser is theshort pulse duration of only 65 msec, well belowthe thermal relaxation time (∼700 msec) of thelayer directly heated by absorption of 10,600 nmphotons. Scanned CW lasers tend to producesomewhat greater ablation and thermal injuryper pass at equal fluences.

In order for laser resurfacing of psoriasis tobe successful, destruction of the entire epidermisand papillary dermis, sites pivotal in the patho-genesis of psoriasis, would logically seem to benecessary. Because the thickness of individualpsoriatic plaques varies markedly, the exact num-ber of passes needed to achieve this effect wouldnot be constant. As resurfacing proceeds deeperinto the dermis, the tissue color of the surfacechanges. Entry into the papillary dermis appearsas a pink color, whereas the deeper papillary der-mis appears gray. When the upper reticular der-mis is ablated, a yellowish base appears [12]. Inthis study, we tried to achieve complete epidermaland papillary dermis ablation by proceeding untilthe first appearance of yellow dermis. Visible tis-sue contraction occurs when the dermis is vapor-ized or heated [12]. This required far more passesof ablation than with normal skin. The elongatednature of the psoriatic epidermis and papillarydermis may simply make them more difficult tovaporize completely. Despite attaining completedestruction of the entire epidermis and papillarydermis in some of the study conditions, almost allof the psoriatic plaques recurred in all subjects. Itseems that vaporization and/or surgical removal(curettage) of psoriatic epidermis and papillarydermis does not always remove the critical site(s)responsible for maintaining a plaque of psoriasis.

It is difficult to reconcile our results withprevious reports of clearing of psoriasis afterCO2,4,5 argon [9] and pulsed dye laser treatments[2,3]. In the case of CO2 and argon lasers, scarringmay be necessary to achieve clearing. Our study isone of the first to use pulsed or scanned ‘‘resur-facing’’ CO2 lasers, which limit thermal damageand scarring. No scarring was observed, and noconsistent therapeutic response either, despitevery aggressive treatment of up to 22 passes ofablation. The remarkable propensity of psoriasisto heal (and to recur after healing) is apparenthere. However, it is difficult to link scarring per seto therapeutic effect with lasers, in view of the

CO2 Resurfacing of Psoriasis 169

Katugampola [2] and Zelickson [3] studies. Inthese studies, a pulsed dye laser that selectivelytargets dermal microvasculature was effectivewithout apparent scarring. One unifying explana-tion (among many possible) is that dermal vesselsdeeper than papillary dermis play a critical role inmaintaining a plaque of psoriasis. Presumably,this would be the superficial and/or deep plexusthat may have been damaged in the previouslyreported laser studies, but not in this study. Al-though some of our results appear promising, atpresent the CO2 laser does not appear to be anacceptable treatment modality for psoriasis. Fur-ther studies are necessary to determine its effec-tiveness and define ideal treatment parameters.

ACKNOWLEDGMENTS

The authors express their gratitude toJoanne Wimberly for her excellent technical as-sistance.

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