Beware of reflectance confocal microscopy artifacts when searching hyphae in acral skin

AnBrasDermatol.2020;95(1):129---132

Anais

Brasileiros

de

Dermatologia

CORRESPONDENCE

Beware

of

reflectance

confocal

microscopy

artifacts

when

searching

hyphae

in

acral

skin

DearEditor,

Weread withinterest thearticlefromVeaseyetal.1 _that

reportedacaseoftineanigraofthepalmwherereflectance confocalmicroscopy(RCM)wasusedtoconfirmtheclinical diagnosis.Tineanigraisapigmentedcutaneoussuperficial mycosis mainly caused by Hortaea werneckii.The typical clinical manifestation of this fungus is a single, brown to blackasymptomaticmaculewithanirregularbordermainly localized on palms or soles because infection is believed to occur as a result of inoculation froma contamination sourcesuchassoil,sewage,wood,orcompostsubsequent totraumaintheaffectedareas.Albeitbeingusuallylarger and lighter in color, these lesionstend toresemble acral neviormelanoma,thusleadingmanyclinicianstoperform unnecessarybiopsies.

RCM is an emerging non-invasive imaging technique that can show hyphae as thin linear and hyper-reflective structuresinthestratumcorneumincutaneoussuperficial mycosis,2,3 _{including tinea nigra}1,4 _{and allows to confirm}

theclinicaldiagnosisandtoavoidconventionalmycological examinationsandskin biopsies1 _{(Fig.1). However,hyphae}

shouldbedifferentiatedfromthecontoursofnormal ker-atinocytes that can form thin lines and from artifacts. Curiously,stellatehyper-reflectivebodiesareoftenvisible inacralskinonRCM,possiblycorrespondingtokeratinocytes membranesinaplanenotparalleltothemicroscope tip.5

Fig.2 shows normal acralskin of a healthy personwhere these artifacts are well visible and are identical to the images presented by Veasey et al.1 _{as hyphae of tinea}

nigra. The authors stated that hyphae identified by RCM in tinea nigra were tortuous, irregular, and short, differ-entfromthemorphologyofthethinandelongatedhyphae of thedermatophytes. However,in our experienceandin the other case of tinea nigra reported in the literature,

夽 _{Howtocitethisarticle:CinottiE,PerrotJL,RubegniP.Beware}

ofreflectanceconfocalmicroscopyartifactswhensearchinghyphae inacralskin.AnBrasDermatol.2020;95:129---30.

夽夽_{StudyconductedattheDepartmentofMedical,Surgicaland}

NeurologicalScience,DermatologySection,UniversityofSiena,S. MariaalleScotteHospital,Siena,Italy.

hyphae of H. werneckii are elongated and thin on RCM. Moreover,itis alsopossible toobservethat theyare sep-tate. The case of Veasey et al.1 _{highlights the difficulty}

of identifying and describing for the first time what is notknownwiththe newimaging techniques andsuggests cautionwhenmaking thefirstdescriptions inthe medical field.

Inconclusion,RCMcanhelptoidentifyhyphaeoftinea nigra as for other superficial cutaneous mycosis, but the presenceofpossibleartifactsthatmaymimicfungal struc-turesinacralskinshouldbeconsideredforthismycosisthat mainlyaffectspalmsandsoles.

Financial

support

Nonedeclared.

Authors’

contribution

ElisaCinotti:Approvalofthefinalversionofthemanuscript; study design and planning; data collection; preparation

Figure1 Reflectanceconfocalmicroscopyimageofacaseof

tineanigrarevealsthinlinearandhyper-reflectivestructuresin

upperpartoftheepidermis(redarrows;theasteriskindicates

130 CORRESPONDENCE

Figure2 Reflectance confocalmicroscopyimage ofnormal

acralskinofahealthypersonshowsartifactspresentingas

stel-latehyper-reflective bodies intheepidermis(yellow arrows;

asterisksindicateacrosyringia).

and writing of the manuscript; critical revision of the manuscript.

Jean Luc Perrot: Approval of the final version of the manuscript; study design and planning; data col-lection, analysis and interpretation; effective participa-tion in research orientation; intellectual participation in propaedeutic and/or therapeutic conduct of studied cases; critical literature review; critical revision of the manuscript.

Pietro Rubegni: Approval of the final version of the manuscript;effectiveparticipationinresearchorientation; intellectual participation in propaedeutic and/or thera-peutic conduct of studied cases; critical revision of the manuscript.

Conflicts

of

interest

Nonedeclared.

References

1.VeaseyJV,AvilaRBde,FerreiraMAMdeO,LazzariniR.Reflectance confocalmicroscopyoftineanigra:comparingimageswith der-moscopyandmycologicalexaminationresults.AnBrasDermatol. 2017;92:568---9.

2.CinottiE,PerrotJL,LabeilleB,CambazardF.Reflectance con-focalmicroscopyforcutaneousinfectionsandinfestations.JEur AcadDermatolVenereol.2016;30:754---63.

3.CinottiE,LabeilleB,CambazardF,PerrotJL.Reflectance confo-calmicroscopyininfectiousdiseases.GItalDermatolEVenereol. 2015;150:575---83.

4.UvaL,Leal-FilipeP,Soares-de-AlmeidaL,FerreiraJ,OliveiraA. Reflectanceconfocalmicroscopyforthediagnosisoftineanigra. ClinExpDermatol.2018;43:332---4.

5.CinottiE,PerrotJL.Topographicandskinphototypevariationsof skinwithspecialemphasisonfacialandacralskin.In:Gonzalez S,editor.Reflectanceconfocalmicroscopyofcutaneoustumors. India:CRCPress;2017.p.120.

ElisaCinotti a,∗_{,JeanLucPerrot} b_,

PietroRubegni a

a_{DepartmentofMedical,SurgicalandNeurological}

Science,DermatologySection,UniversityofSiena,S. MariaalleScotteHospital,Siena,Italy

b_{DepartmentofDermatology,UniversityHospitalof}

Saint-Etienne,Saint-Etienne,France

∗_{Correspondingauthor.}

E-mail:elisacinotti@gmail.com(E.Cinotti). Received28January2019;accepted24April2019

https://doi.org/10.1016/j.abd.2019.04.013

0365-0596/©2019SociedadeBrasileiradeDermatologia. PublishedbyElsevierEspa˜na,S.L.U.Thisisanopenaccessarticle undertheCCBYlicense(http://creativecommons.org/licenses/ by/4.0/).

Beware

of

reflectance

confocal

microscopy

artifacts

when

searching

hyphae

in

acral

skin

---Reply

DearEditor,

IwouldliketothankCinottietal.fortheirinterestinour paperabouttineanigra’sfindingsatconfocalmicroscopy,as wellastheopportunityofferedbytheeditorsofthisjournal

夽 _{Howtocitethisarticle:VeaseyJV.Bewareofreflectance}

con-focalmicroscopyartifactswhen searchinghyphae inacralskin ---Reply.AnBrasDermatol.2020;95:130---2.

夽夽_{StudyconductedattheDermatologyClinic,HospitaldaSanta}

CasadeMisericórdiadeSãoPaulo,SãoPaulo,SP,Brazil.

to answer the points raised by the authors in the article ‘‘Bewareofreflectanceconfocalmicroscopyartifactswhen searchinghyphaeinacralskin’’.

Theetiologicalagentoftineanigra,Hortaeawernekii,is adematiaceousgeophilicfungus.Thedermoscopicfeatures of thisdiseaseconsist of afibrillarhyperchromic pattern, and the direct mycological examination (DME) presents shortandthickdematiaceoushyphae,correspondingtothe described dermoscopicfindings.1,2 _{Othercasesseen inour}

servicewithfungalcultureisolatingH.wernekiiare compa-tiblewiththesefindings(Fig.1).

Suchfactshadledustobelievethattheimages identi-fiedbyreflectanceconfocalmicroscopy(RCM)inourarticle wouldbecompatiblewiththehyphaeofH.wernekii para-sitizingtheepidermis.Itisnoteworthythatthemorphology ofshortthickstructurespresentedat dermoscopic exami-nationand DMEwerecompatiblewiththoseevidenced by theRCM.3