Osteonevus of Nanta: a case report in a combined melanocytic nevus,

AnBrasDermatol.2020;95(3):351---354

Anais

Brasileiros

de

Dermatologia

DERMATOPATHOLOGY

Osteonevus

of

Nanta:

a

case

report

in

a

combined

melanocytic

nevus

夽,夽夽

Elaine

Dias

Melo

_,

_Patrícia

_Amaral

_Couto

_,

_Antônio

_Pedro

_Mendes

_Schettini

_,

Carlos

Alberto

Chirano

Rodrigues

a_{ServiceofDermatology,Fundac¸ãodeDermatologiaTropicaleVenereologiaAlfredodaMatta,Manaus,AM,Brazil} b_{ServiceofDermatologySurgery,Fundac¸ãodeDermatologiaTropicaleVenereologiaAlfredodaMatta,Manaus,AM,Brazil}

Received4December2018;accepted24April2019 Availableonline19March2020

KEYWORDS Heterotopic; Nevus,blue; Nevus,intradermal; Nevus,pigmented; Ossification; Osteoma

Abstract Secondary osteomacutis isaphenomenon thatmay occur inseveralconditions. WhenitoccursinamelanocyticnevusitisnamedosteonevusofNanta,aneventconsidered uncommonandcharacterizedbythepresenceofboneformationadjacentorinterposedwith melanocytic cells.Therearereportsofitsoccurrenceinvarious melanocyticlesions,being morefrequentlyassociatedwithintradermalnevus.WereportacaseofosteonevusofNanta incombinednevus,possiblythefirstdescriptionofthisassociation.

©2020SociedadeBrasileira deDermatologia.PublishedbyElsevierEspa˜na,S.L.U.Thisisan openaccessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).

Introduction

Secondaryskinossificationisaphenomenonthatcanoccur in several conditions, such as pilomatricoma, basal cell carcinoma,acne,scars,mixedskintumors,sitesof inflam-mationandtrauma.1 _{Itsoccurrenceinmelanocytic nevus,}

called osteonevusof Nanta, appears to be an uncommon

夽 _{How to citethis article: Melo ED, Couto PA, Schettini APM,}

RodriguesCAC.OsteonevusofNanta:acasereportinacombined melanocyticnevus.AnBrasDermatol.2020;95:348---51.

夽夽_{StudyconductedattheFundac¸ãodeDermatologiaTropicale}

VenereologiaAlfredodaMatta,Manaus,AM,Brazil.

∗_{Correspondingauthor.}

E-mail:[email protected](E.D.Melo).

eventwithanestimatedincidencefrom0.6%to1.45%among pigmentedtumors.2

The osteonevus of Nanta is characterized by the pres-enceofadjacentbonetissueorinterposedwithmelanocytic cells,3,4 _{usually located on the upper trunk and with}

predilectionforfemale.2

Wereportthecaseofawomanwithexuberantlesionon thescalp,whose histopathologicalanalysiswasconclusive of osteonevusof Nanta, being possibly the firstreport of thisassociation.

Case

report

A 38 year-old woman with an occipital lesion since she was born, which increased in the last 14 years, without

https://doi.org/10.1016/j.abd.2019.04.017

0365-0596/©2020SociedadeBrasileiradeDermatologia.PublishedbyElsevierEspa˜na,S.L.U.ThisisanopenaccessarticleundertheCC BYlicense(http://creativecommons.org/licenses/by/4.0/).

352 MeloEDetal.

Figure1 (A) Exophytic,pedunculatedtumor offibroelastic consistency,measuring3.0×2.0cm, onthe occipitalregion; (B) appearanceaftersurgicalremoval.

Figure 2 Diffuse proliferation of pigmented epithelioid melanocyticcellsinthepapillarydermiscompatiblewith intra-dermalnevus(Hematoxylin&eosin,×100).

associatedsymptomatology.Attheexamination,therewas anexophytic,pedunculated,normocromictumorwith irreg-ularsurface anddepressedareaswithdarkbrowntoblue pigmentation, fibroelastic consistency, measuring about 3×2cm in diameter (Fig.1). The patienthad no comor-bidities,but sheclaimed tobea user of illicit drugs. We performedsurgicalexcision ofthelesionfordiagnosisand treatment,withfusiformexcision andprimarysuturewith simplestitches(Fig.2).

Thehistopathologicalanalysisshoweddiffuse prolifera-tionof melanocytes arrangedin nests of regular sizeand shapeinthe papillarydermis and instrings in the reticu-lardermissurroundingadjacentstructureswithfocalarea ofmelanocytesofdendriticpatternwithabundantmelanic pigmentinthecytoplasm.Inadditiontocollagen fibropla-sia,therewasaforeignbodytypegranulomatousreaction aroundfree hair shaft and homogeneousbone formations compatible with cutaneous ossification. The histological diagnosiswasosteonevusof Nanta ina combinednevus ---intradermalandblue(Figs.3---5).Theimmunohistochemical

Figure3 Spindleanddendriticpigmentedcellsdistributedin bundlesinthedermis(Hematoxylin&eosin,x400).

studyconfirmedthemelanocyticnatureofthelesion,with positivityforthemarkersS-100,MART-1,gp100.

Discussion

The firstreportofossification ina melanocyticnevuswas madein1908byHeidingsfeld,althoughthephenomenonwas detailedpublishedjustin1911 byNanta,when itbecame knownasosteonevusofNanta.2

OsteonevusofNanta:acasereportinacombinedmelanocyticnevus 353

Figure 4 Fibroplasia, foreign body type granulomatous reaction around the free-haired shaft and bone formations compatiblewith cutaneous ossification Hematoxylin & eosin, x400).

Figure5 Immunohistochemicalstudydemonstrating positiv-ityforMelanAconfirmingthemelanocyticnatureofthelesion.

From its initial description, the phenomenon was reportedinseveralmelanocyticlesionssuchasbluenevus, Spitz’snevus,5_{Becker’s nevus,}6_{beingtheassociationwith}

intradermalmelanocyticnevusthemostcommom.4

Accordingtotheliterature,thelesionsaremostlylocated intheheadandneck,especiallyontheface,beinglessthan 5%in other locations,asforearms.2 _{It ismorecommonin}

women,2,7_{andtheageisvariable,withahigherfrequency}

intheelderly.3,4_{Inthecasereported,thelocationandsex}

ofthepatientareconsistentwiththeliteraturedata.

Aboutitspathophysiology,disembrioplasia (hamartoma-tous lesion) and metaplasia are the main mechanisms postulated sofar toexplain the occurrence of the ossifi-cation of theselesions.According to thedisembrioplasia, there would be the presence of primitive mesenchymal cells of osteocytes at erroneous sites with simultaneous expression of structures of ectodermal and mesodermal origin.8_{Inthemetaplasiamechanismtherewouldbechronic}

inflammation, trauma or neoplastic proliferation indu-cingdifferentiationofdermalfibroblastsintoosteoblasts.8

In chronic inflammation/trauma a follicular distortion or obstruction caused by melanocytes or repetitive trauma of the follicle induced by the removal of hairs from the nevus would lead to follicular rupture, with consequent inflammationandmetaplasia.4,8_{Intheneoplasticprocesses}

desmoplasiawould make the primitive dermal mesenchy-mal cells capable of producing bone.9 _{A third possibility}

wouldbethat thesimple interactionbetweennevus cells andmesenchymaltissuecouldresultincellmetaplasiaand consequentossification.3,4

Regardingthehigherincidenceofosteonevusinfemale reportedin alarge partof thestudies,it isbelieved that estrogen has a potential role in bone formation.4 _Since

osteoblasts have receptors for estrogens, this interaction wouldresultintheiractivationandblockadebone resorp-tionbyosteoclasts.3,10_{However,thereisalackofstudiesto}

provetheimportanceofthismechanismintheossification processofmelanocyticnevi.

In the histological analysis, ossification is usually observedassmallislandsoflamellaroramorphouscompact boneatthebaseofthemelanocyticlesion,3_{inthereticular}

dermisnearhairfollicles,4,10_{assingleormultiplefocus.}3_In

somecases,bonetrabecularlesionswithbonemarrowand adipocytesmaybepresent.3_{Mononuclearinfiltrate,foreign}

bodygranulomaormixedgranulomasarefrequentfindings.2

Inthe case reportedtherewasthe characterizationof combinednevus---intradermalmelanocyticnevusandblue nevus---associatedwiththepresenceofhomogeneousbone tissuein thereticulardermisnear hairfollicles anda for-eign body type granulomatous reaction. No reports have been identified in the literature about combined nevus ossification,which is probablythefirst descriptionof this association.

Thefindingsofossification nearhair follicleand granu-lomatousreactionoftheforeignbodytype,associatedwith thelocalizationof thelesioninthescalp,siterich inhair folliclesandtargetofrepetitivetrauma,guidethe reason-ing regarding the possibility of metaplasia resulting from a chronic follicular inflammatory process, leading to sec-ondaryossificationofthecombinedmelanocyticnevus.

CulverandBurgdorfin1993reportedtheonlycaseinthe literatureofmalignantmelanomaassociatedwith osteone-vusofNanta.Inthereport,thefemalepatienthadextensive superficialmelanomaandintradermalnevuswithtwo ossifi-cationfociatitsbase.9_{Itisnotedthatthereisapossibility}

of ossification in melanomas, but it occursin the middle oftumordesmoplasia,differentfromthecasereportedby theseauthorsthatboneformationwasatthebasisof intra-dermalnevus.

Althoughthephenomenondoesnotappeartoberelated toapoorprognosis,thepossibilityofmetaplasiaasa patho-physiologicalmechanismandanassociationwithmelanoma9

354 MeloEDetal. becometheosteonevoofNantaalesionwithpotential

clin-icalimportance. Therefore, the findings of ossification in excisedmelanocyticlesionsshouldnotbeunderestimated andnotreported.

Financial

support

Nonedeclared.

Author’s

contributions

ElaineDiasMelo:Conceptionandplanningofthestudy; elab-orationandwritingofthemanuscript;obtaining, analysis, andinterpretationofthedata;intellectualparticipationin thepropaedeuticand/ortherapeuticconductofthestudied cases;criticalreviewoftheliterature.

Patrícia Amaral Couto: Elaboration and writing of the manuscript;obtaining, analysis, andinterpretation of the data;criticalreviewoftheliterature.

Antônio Pedro Mendes Schettini: Approval of the final versionof the manuscript; elaboration andwriting of the manuscript;effectiveparticipationinresearchorientation; critical review of the literature; critical review of the manuscript.

CarlosAlbertoChiranoRodrigues:Conceptionand plan-ning of the study; effective participation in research orientation;intellectual participation in thepropaedeutic and/ortherapeuticconductofthestudiedcases.

Conflicts

of

interest

Nonedeclared.

Acknowledgment

To Dr. Patrícia Motta de Morais for her assistance in the histopathologicaldiagnosisandrevisionofthemanuscript.

References

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