Review Article Acne Scars: Pathogenesis, Classification and Treatment

14 Pages·2014·2.77 MB·English

HindawiPublishingCorporation
DermatologyResearchandPractice
Volume2010,ArticleID893080,13pages
doi:10.1155/2010/893080
Review Article
Acne Scars: Pathogenesis, Classification and Treatment
GabriellaFabbrocini,M.C.Annunziata,V.D’Arco,V.DeVita,G.Lodi,
M.C.Mauriello,F.Pastore,andG.Monfrecola
DivisionofClinicalDermatology,DepartmentofSystematicPathology,UniversityofNaplesFedericoII,
ViaSergioPansini5,80133Napoli,Italy
CorrespondenceshouldbeaddressedtoGabriellaFabbrocini,[email protected]
Received17March2010;Revised7September2010;Accepted28September2010
AcademicEditor:DanielBerg
Copyright©2010GabriellaFabbrocinietal.ThisisanopenaccessarticledistributedundertheCreativeCommonsAttribution
License,whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperly
cited.
Acne has a prevalence of over 90% among adolescents and persists into adulthood in approximately 12%–14% of cases with
psychologicalandsocialimplications.Possibleoutcomesoftheinflammatoryacnelesionsareacnescarswhich,althoughtheycan
betreatedinanumberofways,mayhaveanegativepsychologicalimpactonsociallifeandrelationships.Themaintypesofacne
scarsareatrophicandhypertrophicscars.Thepathogenesisofacnescarringisstillnotfullyunderstood,butseveralhypotheses
havebeenproposed.Therearenumeroustreatments:chemicalpeels,dermabrasion/microdermabrasion,lasertreatment,punch
techniques, dermal grafting, needling and combined therapies for atrophic scars: silicone gels, intralesional steroid therapy,
cryotherapy,andsurgeryforhypertrophicandkeloidallesions.Thispapersummarizesacnescarpathogenesis,classificationand
treatmentoptions.
1.Introduction the quality of sebum lipids, androgen activity, proliferation
ofPropionibacteriumacnes(P.acnes)withinthefollicleand
Acne has a prevalence of over 90% among adolescents [1] follicularhyperkeratinization[6].Increasedsebumexcretion
and persists into adulthood in approximately 12%–14% contributes to the development of acne. Neutral and polar
of cases with psychological and social implications of high lipidsproducedbysebaceousglandsserveavarietyofrolesin
gravity[2,3]. signal transduction and are involved in biological pathways
Allbodyareaswithhighconcentrationsofpilosebaceous [7]. Additionally, fatty acids act as ligands of nuclear
glandsareinvolved,butinparticulartheface,backandchest. receptors such as PPARs. Sebaceous gland lipids exhibit
Inflammatory acne lesions can result in permanent scars, direct pro- and anti-inflammatory properties, whereas the
theseverityofwhichmaydependondelaysintreatingacne inductionof5-lipoxygenaseandcyclooxygenase-2pathways
patients.Theprevalenceandseverityofacnescarringinthe in sebocytes leads to the production of proinflammatory
populationhasnotbeenwellstudied,althoughtheavailable lipids [8]. Furthermore, hormones like androgens control
literature is usually correlated to the severity of acne [4]. sebaceous gland size and sebum secretion. In cell culture,
2133 volunteers aged 18 to 70 from the general population androgens only promote sebocyte proliferation, whereas
showed that nearly 1% of people had acne scars, although PPARligandsarerequiredfortheinductionofdifferentiation
only 1 in 7 of these were considered to have “disfiguring andlipogenicactivity[9].Ontheotherhand,keratinocytes
scars”[5].Severescarringcausedbyacneisassociatedwith and sebocytes may be activated by P. acnes via TLR, CD14,
substantialphysicalandpsychologicaldistress,particularlyin and CD1 molecules [10]. Pilosebaceous follicles in acne
adolescents. lesions are surrounded by macrophages expressing TLR2
on their surface. TLR2 activation leads to a triggering of
2.Pathogenesis the transcription nuclear factor and thus the production of
cytokines/chemokines,phenomenaobservedinacnelesions.
Thepathogenesisofacneiscurrentlyattributedtomultiple Furthermore, P. acnes induces IL-8 and IL-12 release from
factors, such as increased sebum production, alteration of TLR2positivemonocytes[11].
2 DermatologyResearchandPractice
All these events stimulate the infrainfundibular inflam-
matoryprocess,follicularrupture,andperifollicularabscess Acnescarssubtypes
formation, which stimulate the wound healing process.
Injurytotheskininitiatesacascadeofwoundhealingevents.
Woundhealingisoneofthemostcomplexbiologicalprocess Icepick Rolling Boxcar Skin
surface
andinvolvessolublechemicalmediators,extracellularmatrix
components, parenchymal resident cells as keratinocytes,
fibroblasts, endothelial cells, nerve cells, and infiltrating
blood cells like lymphocytes, monocytes, and neutrophils,
collectively known as immunoinflammatory cells. Scars
SMAS
originateinthesiteoftissueinjuryandmaybeatrophicor
hypertrophic.Thewoundhealingprocessprogressesthrough
3stages:(1)inflammation,(2)granulationtissueformation, Figure1:Acnescarssubtypes.
and(3)matrixremodeling[12,13].
(1)Inflammation. Blanching occurs secondary to vaso-
constriction for hemostasis. After the blood flow
has been stopped, vasodilatation and resultant ery-
thema replace vasoconstriction. Melanogenesis may
also be stimulated. This step plays an important
role in the development of postacne erythema
and hyperpigmentation. A variety of blood cells,
including granulocytes, macrophages, neutrophils
lymphocytes, fibroblasts, and platelets, are activated
and release inflammatory mediators, which ready
the site for granulation tissue formation [14]. By
examiningbiopsyspecimensofacnelesionsfromthe Figure2:Icepickscars.
backofpatientswithseverescarsandwithoutscars,
Hollandetal.foundthattheinflammatoryreaction
at the pilosebaceous gland was stronger and had a
longer duration in patients with scars versus those for ECM remodeling [18]. As a consequence, an
without;inaddition,theinflammatoryreactionwas imbalance in the ratio of MMPs to tissue inhibitors
slower in those with scars versus patients who did of MMPs results in the development of atrophic
notdevelopscars.Theyshowedastrongrelationship or hypertrophic scars. Inadequate response results
between severity and duration of inflammation and in diminished deposition of collagen factors and
thedevelopmentofscarring,suggestingthattreating formation of an atrophic scar while, if the healing
early inflammation in acne lesions may be the best responseistooexuberant,araisednoduleoffibrotic
approachtopreventacnescarring[15]. tissueformshypertrophicscars[19].
(2)Granulation Tissue Formation. Damaged tissues are
repaired and new capillaries are formed. Neu- 3.Morphology,Histology,andClassification
trophils are replaced by monocytes that change
intomacrophagesandreleaseseveralgrowthfactors Scarringcanoccurasaresultofdamagetotheskin during
including platelet-derived growth factor, fibroblast thehealingofactiveacne.Therearetwobasictypesofscar
growthfactor,andtransforminggrowthfactorsαand dependingonwhetherthereisanetlossorgainofcollagen
β, which stimulate the migration and proliferation (atrophic and hypertrophic scars). Eighty to ninety percent
of fibroblasts [16]. New production of collagen by ofpeoplewithacnescarshavescarsassociatedwithalossof
fibroblastsbeginsapproximately3to5daysafterthe collagen(atrophicscars)comparedtoaminoritywhoshow
woundiscreated.Earlyon,thenewskincomposition hypertrophicscarsandkeloids.
is dominated by type III collagen, with a small
percentage (20%) of type I collagen. However, the
3.1. Atrophic Scars. Atrophic acne scars are more common
balance of collagen types shifts in mature scars
than keloids and hypertrophic scars with a ratio 3:1. They
to be similar to that of unwounded skin, with
havebeensubclassifiedintoicepick,boxcar,androllingscars
approximately80%oftypeIcollagen[17].
(Figure1andTable1).Withatrophicscars,theicepicktype
(3)Matrix Remodelling. Fibroblasts and keratinocytes represents 60%–70% of total scars, the boxcar 20%–30%,
produceenzymesincludingthosethatdeterminethe androllingscars15%–25%[20].
architecture of the extracellular matrix metallopro- Icepick:narrow(2mm),punctiform,anddeepscarsare
teinases (MMPs) and tissue inhibitors of MMPs. known as icepick scars. With this type of scar, the opening
MMPs are extracellular matrix (ECM) degrading istypicallywiderthanthedeeperinfundibulum(forminga
enzymes that interact and form a lytic cascade “V”shape)(Figure2).
DermatologyResearchandPractice 3
Table1:Acnescarmorphologicalclassification(adaptedfrom[20]).
AcneScarsSubtype ClinicalFeatures
Icepickscarsarenarrow(<2mm),deep,sharplymarginatedepithelialtractsthatextendvertically
Icepick
tothedeepdermisorsubcutaneoustissue.
Rollingscarsoccurfromdermaltetheringofotherwiserelativelynormal-appearingskinandare
Rolling usuallywiderthan4to5mm.Abnormalfibrousanchoringofthedermistothesubcutisleadsto
superficialshadowingandarollingorundulatingappearancetotheoverlyingskin.
Boxcar
Boxcarscarsareroundtoovaldepressionswithsharplydemarcatedverticaledges,similarto
Shallow
varicellascars.Theyareclinicallywideratthesurfacethanicepickscarsanddonottapertoa
<3mmdiameter
pointatthebase.
>3mmdiameter
Deep
Theymaybeshallow(0.1–0.5mm)ordeep(≥0.5mm)andaremostoften1.5to4.0mmin
<3mmdiameter
diameter.
>3mmdiameter
tool [22] based on the type of scar and the number of
scars.Thissystemassignsfewerpointstomacularandmild
atrophicscoresthantomoderateandsevereatrophicscores
(macularormildlyatrophic:1point;moderatelyatrophic:2
points;punchedoutorlinear-troughedseverescars:3points;
hyperplastic papular scars: 4 points). The multiplication
factorfortheselesiontypesisbasedonthenumericalrange
whereby,foronetotenscars,themultiplieris1;for11–20it
is2;formorethan20itis3.
The ECCA (Echelle d’Evaluation clinique des Cicatrices
d’acne´) for facial acne scarring is also a quantitative scale,
designed for use in clinical practice with the aim of
Figure3:Boxcarscars.
standardizing discussion on scar treatment and it is based
onthesumofindividualtypesofscarsandtheirnumerical
extent. Scar types considered to be more visibly disfiguring
Rolling: dermal tethering of the dermis to the subcutis were weighted more heavily. Specific scar types and their
characterizesrollingscars,whichareusuallywiderthan4to associated weighting factors were the following: atrophic
5mm.Thesescarsgivearollingorundulatingappearanceto scars with diameter less than 2mm: 15; U-shaped atrophic
theskin(“M”shape).Boxcar:roundorovalscarswithwell- scars with a diameter of 2–4mm: 20; M-shaped atrophic
established vertical edges are known as boxcar scars. These scarswithdiametergreaterthan4mm:25;superficialelastol-
scars tend to be wider at the surface than an icepick scar ysis:30;hypertrophicscarswithalessthan2-yearduration:
and do not have the tapering V shape. Instead, they can be 40; hypertrophic scars of greater than 2-year duration: 50.
visualizedasa“U”shapewithawidebase.Boxcarscarscan A semiquantitative assessment of the number of each of
beshallowordeep(Figure3). thesescartypeswasthendeterminedwithafour-pointscale,
Sometimes the 3 different types of atrophic scars can in which 0 indicates no scars, 1 indicates less than five
be observed in the same patients and it can be very scars, 2 indicates between five and 20 scars, and 3 indicates
difficult to differentiate between them. For this reason morethan20scars.Withthismethod,therelativeextentof
severalclassificationsandscaleshavebeenproposedbyother scarring for each scar type was calculated. The total score
authors. Goodman and Baron proposed a qualitative scale can vary from 0 to 540. In recent studies on the reliability
and then presented a quantitative scale [21, 22]. Dreno et of this scale, seven dermatologists underwent a 30-min
al.introducedtheECCAscale(Echelled’EvaluationClinique trainingsessionpriortotheevaluationoftenacnepatients.
desCicatricesd’Acne´)[23]. Therewasnostatisticaldifferenceinscoregradingbetween
The qualitative scarring grading system proposed by participating dermatologists. The global scores, however,
GoodmanandBaron[9]issimpleanduniversallyapplicable. varied from a minimum of 15 to a maximum of 145.
Accordingtothisclassification,fourdifferentgradescanbe Unfortunately,astatisticalestimateofreliabilitywithinand
used to identify an acne scar, as shown in Table2. Often between raters was not provided. The potential advantages
(especiallyinthoseaffectedwithmildacne)thepatternand of this system include independent accounting of specific
grading is easy to achieve but, in the observation of severe scar types, thereby providing for separate atrophic and
cases,differentpatternsaresimultaneouslypresentandmay hypertrophicsubscoresinadditiontototalscores.Potential
bedifficulttodifferentiate.Thestandardapproachadopted shortcomingsincluderestrictiontofacialinvolvement,time
by Goodman and Baron describes a grading pattern and intensity,andundeterminedclinicalrelevanceofscoreranges
theydevelopedaquantitativeglobalacnescarringassessment [21].
4 DermatologyResearchandPractice
Table2:Qualitativescarringgradingsystem(adaptedfrom[21]).
GradesofPost
Levelofdisease Clinicalfeatures
AcneScarring
Thesescarscanbeerythematous,hyper-orhypopigmentedflatmarks.
1 Macular Theydonotrepresentaproblemofcontourlikeotherscargradesbutof
color.
Mildatrophyorhypertrophyscarsthatmaynotbeobviousatsocial
distancesof50cmorgreaterandmaybecoveredadequatelybymakeupor
2 Mild
thenormalshadowofshavedbeardhairinmenornormalbodyhairif
extrafacial.
Moderateatrophicorhypertrophicscarringthatisobviousatsocial
distancesof50cmorgreaterandisnotcoveredeasilybymakeuporthe
3 Moderate
normalshadowofshavedbeardhairinmenorbodyhairifextrafacial,but
isstillabletobeflattenedbymanualstretchingoftheskin(ifatrophic).
Severeatrophicorhypertrophicscarringthatisevidentatsocialdistances
greaterthan50cmandisnotcoveredeasilybymakeuporthenormal
4 Severe
shadowofshavedbeardhairinmenorbodyhairifextrafacialandisnot
abletobeflattenedbymanualstretchingoftheskin.
3.2. Hypertrophic and Keloidal Scars. Hypertrophic and scars are the major clinical indications for facial chemical
keloidal scars are associated with excess collagen deposi- peeling[26,27].
tion and decreased collagenase activity. Hypertrophic scars As regards acne scars, the best results are achieved in
are typically pink, raised, and firm, with thick hyalinized macular scars. Icepick and rolling scars cannot disappear
collagen bundles that remain within the borders of the completelyandneedsequentialpeelingstogetherwithhome-
original site of injury. The histology of hypertrophic scars caretreatmentwithtopicalretinoidsandalphahydroxyacids
is similar to that of other dermal scars. In contrast, keloids [28, 29]. The level of improvement expected is extremely
formasreddish-purplepapulesandnodulesthatproliferate variable in different diseases and patients. For example, ice
beyond the borders of the original wound; histologically, pickacnescarsinapatientwithhyperkeratoticskinareonly
theyarecharacterizedbythickbundlesofhyalinizedacellular mildly improved even if skin texture is remodeled. On the
collagenarrangedinwhorls.Hypertrophicandkeloidalscars other hand, a patient with isolated box scars can obtain a
aremorecommonindarker-skinnedindividualsandoccur significantimprovementbyapplicationofTCAat50%–90%
predominantlyonthetrunk. onthesinglescars.
Severalhydroxyacidscanbeused.
4.Treatment
(A) Glycolic Acid. Glycolic acid is an alpha-hydroxy acid,
soluble in alcohol,derived fromfruit and milk sugars.Gly-
Newacquisitionsbytheliteraturehaveshowedthatpreven-
colicacidactsbythinningthestratumcorneum,promoting
tionisthemainstepinavoidingtheappearanceofpost-acne
epidermolysisanddispersingbasallayermelanin.Itincreases
scars.Geneticfactorsandthecapacitytorespondtotrauma
dermal hyaluronic acid and collagen gene expression by
are the main factors influencing scar formation [24]. A
increasingsecretion ofIL-6[30].Theprocedureiswelltol-
numberoftreatmentsareavailabletoreducetheappearance
eratedandpatientcomplianceisexcellent,butglycolicacid
ofscars.First,itisimportanttoreduceasfaraspossiblethe
peels are contraindicated in contact dermatitis, pregnancy,
duration and intensity of the inflammation, thus stressing
and in patients with glycolate hypersensitivity. Side effects,
the importance of the acne treatment. The use of topical
such as temporary hyperpigmentation or irritation, are not
retinoids is useful in the prevention of acne scars but more
very significant [31]. Some studies showed that the level of
thananyothermeasure,theuseofsiliconegelhasaproven
skindamagewithglycolicacidpeelincreasesinadose-and
efficacyinthepreventionofscars,especiallyforhypertrophic
time-dependent manner. The acid at the higher concentra-
scarsandkeloids.
tion(70%)createdmoretissuedamagethantheacidatthe
lowerconcentration(50%)comparedtosolutionswithfree
4.1.AtrophicScars acid.Anincreaseinthetransmembranepermeabilitycoeffi-
cientisobservedwithadecreaseinpH,providingapossible
4.1.1. Chemical Peels. By chemical peeling we mean the explanationfortheeffectivenessofglycolicacidinskintreat-
processofapplyingchemicalstotheskintodestroytheouter ment[32].Thebestresultsachievedforacnescarsregardfive
damagedlayersandacceleratetherepairprocess[25]. sequentialsessionsof70%glycolicacidevery2weeks.
Chemicalpeelingisusedforthereversalofsignsofskin
aging and for the treatment of skin lesions as well as scars, (B) Jessner’s Solution. Formulated by Dr. Max Jessner, this
particularly acne scars. Dyschromias, wrinkles, and acne combination of salicylic acid, resorcinol, and lactic acid
DermatologyResearchandPractice 5
in 95% ethanol is an excellent superficial peeling agent. a light superficial peel with diffusion encompassing the full
Resorcinolisstructurallyandchemicallysimilartophenol.It thicknessoftheepidermis;40%–50%canproduceinjuryto
disruptstheweakhydrogenbondsofkeratinandenhances- the papillary dermis; and finally, greater than 50% results
penetration of other agents [33]. Lactic acid is an alpha in injury extending to the reticular dermis. Unfortunately
hydroxy acid which causes corneocyte detachment and theuseofTCAconcentrationsabove35%TCAcanproduce
subsequent desquamation of the stratum corneum [34]. unpredictable results such as scarring. Consequently, the
As with other superficial peeling agents, Jessner’s peels medium depth chemical peel should only be obtained with
are well tolerated. General contraindications include active the combination of 35% TCA. The use of TCA in con-
inflammation, dermatitis or infection of the area to be centrations greater than 35%, should be avoided. It can be
treated, isotretinoin therapy within 6 months of peeling preferredinsomecasesofisolatedlesionsorfortreatmentof
and delayed or abnormal wound healing. Allergic contact isolatedicepickscars(TCACROSS)[49].Whenperformed
dermatitis and systemic allergic reactions to resorcinol are properly,peelingwithTCAcanbeoneofthemostsatisfying
rareandneedtobeconsideredasabsolutecontraindications procedures in acne scar treatment but it is not indicated
[35,36]. fordarkskinbecauseofthehighriskofhyperpigmentation
[50].
(C) Pyruvic Acid. Pyruvic acid is an alpha-ketoacid and
an effective peeling agent [37]. It presents keratolytic, (F)TCACross. InourexperiencetheTCACROSStechnique
antimicrobialandsebostaticpropertiesaswellastheability has shown high efficacy in the case of few isolated scars
to stimulate new collagen production and the formation of on healthy skin. CROSS stands for chemical reconstruction
elastic fibers [38]. The use of 40%–70% pyruvic acid has of skin scars method and involves local serial application
been proposed for the treatment of moderate acne scars of high concentration TCA to skin scars with wooden
[39,40].Sideeffectsincludedesquamation,crustinginareas applicators sized via a number 10 blade to a dull point to
of thinner skin, intense stinging, and a burning sensation approximate the shape of the scar. No local anesthesia or
during treatment. Pyruvic acid has stinging and irritating sedation is needed to perform this technique [51]. Unlike
vaporsfortheupperrespiratorymucosa,anditisadvisable the reports found in the literature, in which 90% TCA is
toensureadequateventilationduringapplication. suggested, our experiences have shown that a lower TCA
concentration (50%) has similar results and much less
(D) Salicylic Acid. Salicylic acid is one of the best peeling adverse reactions [52]. TCA is applied for a few seconds
agentsforthetreatmentofacnescars[41].Itisabetahydroxy untilthescardisplaysawhitefrosting.Emollientsthenneeds
acid agent which removes intercellular lipids that are cova- to be prescribed for the following 7 days and high photo-
lentlylinkedtothecornifiedenvelopesurroundingcornified protectionisrequired.Theprocedureshouldberepeatedat
epithelioidcells.Themostefficaciousconcentrationforacne 4-week intervals, and each patient receives a total of three
scarsis30%inmultiplesessions,3–5times,every3-4weeks treatments. Our experiences have shown that, compared
[42–44].Thesideeffectsofsalicylicacidpeelingaremildand with other procedures, this technique can avoid scarring
transient. These include erythema and dryness. Persistent and reduce the risk of hypopigmentation by sparing the
postinflammatory hyperpigmentation or scarring are very adjacentnormalskinandadnexalstructures[53](Figures4
rare and for this reason it is used to treat dark skin [45]. and5).
Rapidbreathing,tinnitus,hearingloss,dizziness,abdominal
cramps, and central nervous system symptoms characterize 4.1.2. Dermabrasion/Microdermabrasion. Dermabrasion
salicylism or salicylic acid toxicity. This has been observed and microdermabrasion are facial resurfacing techniques
with 20% salicylic acid applied to 50% of the body surface thatmechanicallyablatedamagedskininordertopromote
[46]. Grimes has peeled more than 1,000 patients with the reepithelialisation. Although the act of physical abrasion of
current20and30%marketedethanolformulationsandhas theskiniscommontobothprocedures,dermabrasion,and
observednocasesofsalicylism[47]. microdermabrasion employ different instruments with a
differenttechnicalexecution[54].Dermabrasioncompletely
(E) Trichloroacetic Acid. The use of trichloroacetic acid removes the epidermis and penetrates to the level of the
(TCA)asapeelingagentwasfirstdescribedbyP.G.Unna,a papillary or reticular dermis, inducing remodeling of the
Germandermatologist,in1882.TCAapplicationtotheskin skin’s structural proteins. Microdermabrasion, a more
causesproteindenaturation,theso-calledkeratocoagulation, superficial variation of dermabrasion, only removes the
resulting in a readily observed white frost [48]. For the outerlayeroftheepidermis,acceleratingthenaturalprocess
purposes of chemical peeling, it is mixed with 100mL of exfoliation [55, 56]. Both techniques are particularly
of distilled water to create the desired concentration. The effective in the treatment of scars and produce clinically
degree of tissue penetration and injury by a TCA solution significantimprovementsinskinappearance.Dermabrasion
is dependent on several factors, including percentage of isperformedunderlocalorgeneralanaesthesia.Amotorized
TCA used, anatomic site, and skin preparation. Selection handpiecerotatesawirebrushoradiamondfraise.Several
of appropriate TCA-concentrated solutions is critical when decadesago,thehandpiecewasmadeofaluminumoxideor
performingapeel.TCAinapercentageof10%–20%results sodiumbicarbonatecrystals,whereasnowdiamondtipshave
inaverylightsuperficialpeelwithnopenetrationbelowthe replacedthesehandpiecestoincreaseaccuracyanddecrease
stratumgranulosum;aconcentrationof25%–35%produces irritation.Thereisoftenasmallpinpointbleedingoftheraw
6 DermatologyResearchandPractice
beneath. Nonablative lasers do not remove the tissue, but
stimulate new collagen formation and cause tightening of
the skin resulting in the scar being raised to the surface.
Amongthenonablativelasersthemostcommonlyusedare
theNdYAGandDiodelasers[61].
Theablativelasersaretechnologieswithahighselectivity
for water. Therefore, their action takes place mainly on the
surfacebutthedepthofactioniscertainlytobecorrelatedto
the intensity of the emitted energy and the diameter of the
spot used. Among the ablative lasers, Erbium technologies
aresoselectiveforwaterthattheiractionisalmostexclusively
ablative.CO lasers,whichpresentlowerselectivityforwater,
2
besides causing ablation are also capable of determining
Figure4:TCACross:patientbeforethetreatment.
a denaturation in the tissues surrounding the ablation
and a thermal stimulus not coagulated for dermal protein.
CO lasers have a double effect: they promote the wound
2
healing process and arouse an amplified production of
myofibroblasts and matrix proteins such as hyaluronic acid
[62].
Clinical and histopathologic studies have previously
demonstrated the efficacy of CO laser resurfacing in the
2
improvement of facial atrophic acne scars, with a 50%–
80% improvement typically seen. The differences in results
reported with apparently similar laser techniques may be
due to variations in the types of scar treated. Candidates
mustpresentaskindiseasewithacneoffforatleast1year;
theyshouldhavestoppedtakingoralisotretinoinforatleast
1 year; they should not have presented skin infections by
Figure5:TCACross:patientafterthetreatment. herpesvirusduringthesixmonthspriortotreatment;they
mustnothaveahistoryofkeloidsorhypertrophicscarring.
Patients with a high skin type phototype are exposed to
woundthatsubsideswithappropriatewoundcare.Patients a higher risk of hyperpigmentation after treatment than
with darker skin may experience permanent skin discol- patientswithlowphototype.
orationorblotchiness.Asregardsthetechniqueofmicroder- All ablative lasers showed high risk of complications
mabrasion,avarietyofmicrodermabradersareavailable.All and side effects. Adverse reactions to the first generation of
microdermabradersincludeapumpthatgeneratesastream ablative lasers can be classified into short-term (bacterial,
of aluminum oxide or salt crystals with a hand piece and herpeticorfungalinfections)andlong-term(persistentery-
vacuum to remove the crystals and exfoliate the skin [57]. thema,hyperpigmentation,scarring)[63,64].Inparticular,
Unlike dermabrasion, microdermabrasion can be repeated scarring after CO laser therapy may be due to the over
2
at short intervals, is painless, does not require anesthesia treatment of the areas (including excessive energy, density,
and is associated with less severe and rare complications, orboth),lackoftechnicalaspects,infection,oridiopathic.It
but it also has a lesser effect and does not treat deep scars isnecessarytotakeintoaccounttheseaspectswhensensitive
[58,59]. areassuchastheeyelids,upperneck,andespeciallythelower
Itisessentialtoconductathoroughinvestigationofthe neckandchestaretreated[65,66].
patient’s pharmacological history to ensure that the patient Nonablative skin remodeling systems have become
has not taken isotretinoin in the previous 6–12 months. increasingly popular for the treatment of facial rhytides
As noted by some studies [60], the use of tretinoin causes and acne scars because they decrease the risk of side
delayedreepithelializationanddevelopmentofhypertrophic effects and the need for postoperative care. Nonablative
scars. technologyusinglong-pulseinfrared(1.450nmdiode,1320
and1064nmneodymium-dopedyttriumaluminumgarnet
4.1.3. Laser Treatment. All patients with box-car scars (Nd:YAG), and 1540nm erbium glass) was developed as
(superficialordeep)orrollingscarsarecandidatesforlaser a safe alternative to ablative technology for inducing a
treatment.Differenttypesoflaser,includingthenonablative controlled thermal injury to the dermis, with subsequent
and ablative lasers are very useful in treating acne scars. neocollagenesisandremodelingofscarredskin[67–72].
Ablative lasers achieve removal of the damaged scar tissue Althoughimprovementwasnotedwiththesenonablative
through melting, evaporation, or vaporization. Carbon lasers, the results obtained were not as impressive as the
dioxidelaserandErbiumYAGlaserarethemostcommonly resultsfromthoseusinglaserresurfacing[71].
used ablative lasers for the treatment of acne scars. These For this reason, a new concept in skin laser therapy,
abrade the surface and also help tighten the collagen fibers called fractional photothermolysis, has been designed to
DermatologyResearchandPractice 7
createmicroscopicthermalwoundstoachievehomogeneous 4.1.5.DermalGrafting. Acnescarsmaybetreatedsurgically
thermal damage at a particular depth within the skin, using procedures such as dermabrasion and/or simple scar
a method that differs from chemical peeling and laser excision,scarpunchelevation,orpunchgrafting[85].
resurfacing.Prior studies using fractionalphotothermolysis The useful modalities available are dermal punch graft-
havedemonstrateditseffectivenessinthetreatmentofacne ing, excision, and facelifting. The selection of these tech-
scars [73] with particular attention for dark skin to avoid niques is dependent on the above classification and the
postinflammatoryhyperpigmentation[74]. patient’sdesireforimprovement[86].
Newer modalities using the principles of fractional
Split-thicknessorfull-thicknessgrafts“take”onabedof
photothermolysis devices (FP) to create patterns of tiny
scartissueordermisfollowingtheremovaloftheepidermis.
microscopic wounds surrounded by undamaged tissues are
The technique is useful in repairing unstable scars from
new devices that are preferred for these treatments. These
chroniclegulcersorX-rayscars.Itcanalsocamouflageacne
devices produce more modest results in many cases than
scars,extensivenevipigmentosus,andtattoos[87,88].Itis
traditional carbon dioxide lasers but have few side effects
prepackaged dermal graft material that is easy to use, safe,
and short recovery periods [75]. Many fractional lasers andeffective[89].
are available with different types of source. A great deal
of experience with nonablative 1550nm erbium doped
4.1.6. Tissue Augmenting Agents. Fat transplantation. Fat is
fractional photothermolysis has shown that the system can
easily available and it has low incidence of side effects[90].
bewidelyusedforclinicalpurposes.
The technique consists of two phases: procurement of the
Anablative30WCO laserdeviceusesablativefractional
2 graft and placement of the graft. The injection phase with
resurfacing (AFR) and combines CO ablation with an FP
2 smallparcelsoffatimplantedinmultipletunnelsallowsthe
system. By depositing a pixilated pattern of microscopic
fatgraftmaximalaccesstoitsavailablebloodysupply.Thefat
ablative wounds surrounded by healthy tissue in a manner
injectedwillnormalizethecontourexceptedwhereresidual
similar to that of FP [76], AFR combines the increased
efficacy of ablative techniques with the safety and reduced scarattachmentsimpedethis.
downtimeassociatedwithFP.
Topographic analysis performed by some authors has 4.1.7. Other Tissue Augmenting Agents. There are many
shown that the depth of acneiform scars has quantifiable new and older autologous, nonautologous biologic, and
objective improvement ranging from 43% to 80% with nonbiologictissueaugmentationagentsthathavebeenused
a mean level of 66.8% [77]. The different experiences in the past for atrophic scars, such as autologous collagen,
of numerous authors in this field have shown that, by bovine collagen, isolagen, alloderm, hyaluronic acid, fibrel,
combiningablativetechnologywithFP,AFRtreatmentscon- artecoll, and silicon, but nowadays, because of the high
stituteasafeandeffectivetreatmentmodalityforacneiform incidence of side effects, the recommended material to use
scarring. Compared to conventional ablative CO devices ishyaluronicacid[91].
2
the side effects profile is greatly improved and, as with
FP, rapid reepithelization from surrounding undamaged 4.1.8. Needling. Skin needling is a recently proposed tech-
tissue is believed to be responsible for the comparatively nique that involves using a sterile roller comprised of a
rapid recovery and reduced downtime noted with AFR series of fine, sharp needles to puncture the skin. At first,
[78–80]. facial skin must be disinfected, then a topical anesthetic is
Pigmentationabnormalitiesfollowinglasertreatmentis applied,leftfor60minutes.Theskinneedlingprocedureis
always a concern. Alster and West reported 36% incidence achievedbyrollingaperformedtoolonthecutaneousareas
of hyperpigmentation when using conventional CO resur- affectedbyacnescars(Figure6),backwardandforwardwith
2
facingcomparedtoaminorityofpatientstreatedwithAFR some pressure in various directions. The needles penetrate
treatments,probablylinkedtoshortenedperiodofrecovery about 1.5 to 2mm into the dermis. As expected, the skin
and posttreatment erythema [81]. The treatment strategy bleeds for a short time, but that soon stops. The skin
is linked to establishing the optimal energy, the interval develops multiple microbruises in the dermis that initiate
betweensessions,andalongerfollow-upperiodtooptimize the complex cascade of growth factors that finally results
treatmentparameters. in collagen production. Histology shows thickening of skin
and a dramatic increase in new collagen and elastin fibers.
4.1.4. Punch Techniques. Atrophic scarring is the more Results generally start to be seen after about 6 weeks but
commontypeofscarringencounteredafteracne.Autologous the full effects can take at least three months to occur and,
and nonautologous tissue augmentation, and the use of as the deposition of new collagen takes place slowly, the
punchreplacementtechniqueshasaddedmoreprecisionand skin texture will continue to improve over a 12 month
efficacytothetreatmentofthesescars[82]. period.Clinicalresultsvarybetweenpatients,butallpatients
The laser punch-out method is better than even depth achievesomeimprovements(Figures7and8).Thenumber
resurfacingforimprovingdeepacnescarsandcanbecom- of treatments required varies depending on the individual
binedwiththeshouldertechniqueorevendepthresurfacing collagenresponse,ontheconditionofthetissueandonthe
accordingtothetypeofacnescar[83]. desired results. Most patients require around 3 treatments
Laserskinresurfacingwiththeconcurrentuseofpunch approximately 4 weeks apart. Skin needling can be safely
excisionimprovesfacialacnescarring[84]. performed on all skin colours and types: there is a lower
8 DermatologyResearchandPractice
Figure6:Needling:theprocedure.
Figure8:Needling:patientafterthetreatment.
4.2.HypertrophicScars
4.2.1.SiliconeGel. Silicone-basedproductsrepresentoneof
themostcommonandeffectivesolutionsinpreventingand
alsointhetreatmentofhypertrophicacnescars.Thesilicone
gel was introduced in the treatment of hypertrophic acne
scarstoovercomethe difficulties in themanagementof sil-
iconesheets.Indeed,thesiliconegelhasseveraladvantages:
it is transparent, quick drying, nonirritating and does not
induce skin maceration, it can be used to treat extensive
scarsandunevenareasofskin.Themechanismofactionis
not fully understood but several hypotheses [95] have been
advanced: (1) the increase in hydration; (2) the increase in
temperature;(3)protectionofthescar;(4)increasedtension
Figure7:Needling:patientbeforethetreatment.
ofO2;(5)actionontheimmunesystem.Thereis,currently,
only one observational open label study, conducted on 57
patients. In this study, the gel was applied on the scars 2
risk of postinflammatory hyperpigmentation than other times daily for 8 weeks with an average improvement in
procedures, such as dermabrasion, chemical peelings, and thethicknessestimatedbetween40%and50%comparedto
laser resurfacing. Skin needling is contraindicated in the baseline.
presence of anticoagulant therapies, active skin infections, Asregardsthetreatmentofalreadyformedhypertrophic
collageninjections,andotherinjectablefillersintheprevious scars,thegelshouldbeappliedinsmallamounts,twicedaily
sixmonths,personalorfamiliarhistoryofhypertrophicand foratleast8weekstoachieveasatisfactoryaestheticresult.
keloidalscars[92,93]. Whereasforthepurposesofprevention,thesamedosageis
recommendedforatleast12–16weeks;thetreatmentshould
be started as soon as possible after the risk of a patient
4.1.9. Combined Therapy. There is a new combination
developinghypertrophicacnescarshasbeenidentified.
therapy for the treatment of acne scars. The first therapy
Treatmentwithsiliconegelcanbeusedinpatientsofany
consists of peeling with trichloroacetic acid, then followed
age and women of childbearing age. Moreover, the silicone
bysubcision,theprocessbywhichthereisseparationofthe
gelcanbeusedthroughouttheyear,includingsummer.
acnescarfromtheunderlyingskinandintheendfractional
laserirradiation.Theefficacyandsafetyofthismethodwas
investigated for the treatment of acne scars. The duration 4.2.2. Intralesional Steroid Therapy. Intralesional injection
of this therapy is 12 months. Dot peeling and subcision of steroids is one of the most common treatments for
wereperformedtwice2-3monthsapartandfractionallaser keloids and hypertrophic scars. It can be used alone or
irradiation was performed every 3-4 weeks. There were no as part of multiple therapeutic approaches. Corticosteroids
significant complications at the treatment sites. It would mayreducethevolume,thickness,andtextureofscars,and
appear that triple combination therapy is a safe and very they can relieve symptoms such as itching and discomfort
effective combination treatment modality for a variety of [96]. The mechanisms of action have not been completely
atrophicacnescars[94]. clarified: in addition to their anti-inflammatory properties,
DermatologyResearchandPractice 9
it has been suggested that steroids exert a vasoconstrictor had only variable success in the past due to the minimal
and an antimitotic activity. It is believed that steroids improvementinahighpercentofpatients[106–108].
arrestpathologicalcollagenproductionthroughtwodistinct On the contrary, the use of pulsed dye laser (PDL) has
mechanisms: the reduction of oxygen and nutrients to the provided encouraging results in the treatment of hyper-
scar with inhibition of the proliferation of keratinocytes trophic/keloidalscarsoverthepast10years.Severalstudies
andfibroblasts[96];thestimulationofdigestionofcollagen have been conducted to investigate how the PDL works on
deposition through block of a collagenase-inhibitor, the hypertrophic/keloidal scars. They have revealed that PDL
alpha-2-microglobulin[97].Duringtheinjectionthesyringe decreases the number and proliferation of fibroblasts and
needleshouldbekeptupright[24].Itisalwayspreferablefor collagenfibersappearlooserandlesscoarse[109].Moreover,
theinjectionstobeprecededbytheapplicationofanesthetic PDL also produces an increase in MMP-I3 (collagenese-
creamsorbeassociatedwithinjectionsoflidocaine[97]. 3) activity and a decrease in collagen type III deposition
Intralesionalsteroidtherapymaybeprecededbyalight [110]. As a consequence, PDL flattens and decreases the
cryotherapy with liquid nitrogen, 10–15 minutes before volume of hypertrophic scars [111, 112], improves texture
injection, to improve the dispersion of the drug in scar [113],andincreaseselasticity[114],usuallyaftertwotothree
tissueandminimizethedepositioninthesubcutaneousand treatments[115].Additionally,pruritisandpainwithinthe
perilesional tissue [98]. The steroid that is currently most scarsaresignificantlyimproved[116].Besides,norecurrence
frequently used in the treatment of hypertrophic scars and or worsening of PDL-treated scars occurs during the 4-
keloidsistriamcinoloneacetonide(10–40mg/mL)[99].The year followup after cessation of treatment [116]. The most
mostcommonadversereactionsarehypopigmentation,skin common side effect of the PDL is purpura which can last
atrophy, telangiectasia, and infections [100]. As for injuries as long as 7–10 days. Blistering can also occur as well as
totheface,theuseofintralesionalsteroidsisrecommended hypo-andhyperpigmentationwhichismorelikelyindarker
for the treatment of individual elements which are skinned individuals [117]. Therefore, the ideal candidates
particularly bulky and refractory to previous less invasive for PDL are patients with lighter skin types (Fitzpatrick
methods. TypesI–III)becauselessmelaninispresenttocompetewith
hemoglobinlaserenergyabsorption[118,119].
4.2.3. Cryotherapy. Cryotherapy with liquid nitrogen can
4.2.5. Surgery. For the correction of large facial scars, W-
significantlyimprovetheclinicalappearanceofhypertrophic
plastyseemstobeoptimal[12].Thistherapeuticprocedure
scarsandkeloidsandalsodeterminetheircompleteregres-
causes a disruption of the scar which makes the lesion
sion.
less conspicuous. Especially in facial surgery, autologous
The low temperatures reached during cryotherapy ses-
skin transplants, namely, full thickness skin transplant or
sionscauseaslowingofbloodflowandcausetheformation
composite fat-skin graft, are another valuable alternative
of intraluminal thrombus hesitant to anoxia and tissue
for achieving wound closure with minimal tension. The
necrosis[101].Ageandsizeofthescarareimportantfactors
preferreddonorsitesforskingraftusedforfacialdefectsare
conditioning the outcome of this technique: younger and
theretro-andpreauricularsitesaswellastheneck[120].
smaller scars are most responsive to cryotherapy [102].
Compared with intralesional injections of corticosteroids,
cryosurgery is significantly more effective than alternative 4.2.6.OtherApproaches. Othertreatmentoptionsforhyper-
methodsforrichlyvascularizedinjuries12monthsyounger trophic acne scars and keloids that can be taken into
[103]. During each session of cryotherapy the patient is account include elastic compression, intralesional injection
usually subjected to 2-3 cycles, each lasting less than 25 of 5-fluorouracil, imiquimod, interferon, radiotherapy, and
seconds. Cryotherapy can also be used before each cycle bleomycin.Alltheseapproaches,however,aremoreeffective
of intralesional injections of steroids to reduce the pain of for the treatment of hypertrophic scars not caused by acne
injectiontherapyandtofacilitatetheinjectionofcortisone, andtheiruseisnotrecommendedduetotheirimpracticality
generatingasmallareaofedemaatthelevelofthescartissue (elastic compression), the lack of clinical experience in the
tobetreated[98].Possibleadversereactionsarerepresented literature (5 FU, interferon, radiotherapy, bleomycin) the
by hypo- and hyperpigmentation, skin atrophy, and pain lackofefficacy(imiquimod),andthehighcosts(interferon).
[102]. With regard to localized lesions to the face, the
possibleoutcomesoffreezingrestricttheuseofcryotherapy
5.Conclusion
in these areas, especially in cases where the scars are
numerous or for dark phenotypes. Therefore, cryotherapy
There are no general guidelines available to optimize acne
can be taken into consideration especially for scars located
scar treatment. There are several multiple management
onthetrunkorforparticularlybulkyscarsontheface.
options,bothmedicalandsurgical,andlaserdevicesareuse-
ful in obtaining significant improvement. Further primary
4.2.4. Pulsed Dye Laser. The use of lasers for hypertrophic research such as randomized controlled trials is needed in
scars and keloids was first proposed by Apfelberg et al. order to quantify the benefits and to establish the duration
[104] and Castro et al. [105] in the 1980s, and since then oftheeffects,thecost-effectiveratioofdifferenttreatments,
morelaserswithvariouswavelengthshavebeenintroduced. andtheevaluationofthepsychologicalimprovementandthe
Unfortunately, laser therapy for hypertrophic scars has qualityoflifeofthesepatients.
10 DermatologyResearchandPractice
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