Pterygium of the Nail - Cutis

continuing medical educationPterygium of the NailBertrand J.S. Richert, MD, Liège, BelgiumAnil Patki, MD, Pune, IndiaRobert L. Baran, MD, Cannes, FranceGOALTo summarize the clinical features and etiologies ofpterygium of the nailOBJECTIVESUpon completion of this activity, dermatologists and general practitioners should be able to:1. Describe the clinical features of pterygium of the nail.2. Discuss the pathogenesis of both dorsal pterygiumand ventral pterygium.3. Identify the causes of dorsal and ventral pterygia.CME Test on page 347.This article has been peer reviewed andapproved by Michael Fisher, MD, Professorof Medicine, Albert Einstein College ofMedicine. Review date: October 2000.This activity has been planned and implementedin accordance with the Essentialsand Standards of the AccreditationCouncil for Continuing Medical Educationthrough the joint sponsorship of AlbertEinstein College of Medicine and QuadrantHealthCom, Inc. The Albert EinsteinCollege of Medicine is accredited by theACCME to provide continuing medical educationfor physicians.Albert Einstein College of Medicinedesignates this educational activity for amaximum of 1.0 hour in category 1 credittoward the AMA Physician’s RecognitionAward. Each physician should claim onlythose hours of credit that he/she actuallyspent in the educational activity.This activity has been planned andproduced in accordance with ACCMEEssentials.Dorsal pterygium is the growth of a projectionof the proximal nail fold that fuses with theunderlying matrix and, subsequently, with thenail bed. As a result, the nail plate is divided into 2lateral segments. Ventral pterygium, a distal extensionof the hyponychium that anchors to the undersurfaceof the nail plate, eventually obliterates thedistal nail groove.Dorsal PterygiumDorsal pterygium, or pterygium unguis, occurs whenthe cul-de-sac of the proximal nail fold (PNF) grad-Dr. Richert is a Consultant Dermatologist in the Dermatology Unit,University of Liège, Belgium. Dr. Patki is from the Indira MedicoClinic, Pune, India. Dr. Baran is Associate Professor, Faculté dePharmacie, Galénique et Cosmétologique, Cedex, France, and isalso with the Nail Disease Center, Cannes, France.REPRINT REQUESTS to Nail Disease Center, 42 Rue des Serbes06400, Cannes, France (Dr. Baran).FIGURE 1. Lichen planus involving both thumbs; lateralremnants of nail keratin are visible.VOLUME 66, NOVEMBER 2000 343

PTERYGIUM OF THE NAILFIGURE 2. Dorsal pterygium involvingone finger after a major trauma.FIGURE 3. Ventral pterygium affectingonly one finger.ually shortens and the nail plate thins until, eventually,the PNF fuses to the matrix and, subsequently,to the nail bed. The resulting nail plate segments progressivelydecrease in size as the pterygium widens,resulting in 2 small remnants involving the PNF.Complete involvement of the matrix and nail bedproduces a total loss of the plate and permanent atrophyof the nail apparatus. Dorsal pterygium is usuallyacquired, but exceptional congenital forms havebeen reported. In a case of nail lichen planus in 1921,Friedman first described pterygium unguis using theterm navellierungsprozess. 1 Dorsal pterygium rarely affectsthe toes; involvement of all 20 toenails has beenreported in only one case.Although pterygium unguis is most commonlycaused by lichen planus (Figure 1), 2 it also may originatefrom burns, radiodermatitis, trauma (Figure 2),and diseases prone to developing adherence bands,including cicatricial pemphigoid, graft versus host disease,toxic epidermal necrolysis, and pemphigus foliaceus(Table I). Peripheral ischemia, intermittentlydetected in Raynaud’s phenomenon 3 or permanentlyfound in atherosclerosis, diabetic vasculopathy, andtype 2 lepra reaction, has been identified as a vascularcause of dorsal pterygium. An idiopathic form ofpterygium unguis, or idiopathic atrophy of the nails,exists, but may be a variation of lichen planus andremains a controversial cause. 4 Congenital forms maybe associated with dyskeratosis congenita, andpterygium formation has been reported in systemiclupus erythematosus and in one case of sarcoidosisinvolving the PNF.Healing of a disease involving the PNF may lead toscarring pterygium formation; however, several factorsthat interfere with the healing of the PNF must appearsimultaneously for this to occur. In patients with dorsalpterygium (excluding the traumatic and congenitaltypes), the main factor is dilatation of the nail capillaryloops and the formation of a slender, microvascularshunt system in them. Although pterygium that344 CUTIS ®

PTERYGIUM OF THE NAILTable I.Causes of Dorsal Pterygium(Pterygium Unguis)AtherosclerosisBurnsCicatricial pemphigoidCongenital etiologyDiabetic vasculopathyDyskeratosis congenitaGraft versus host diseaseIdiopathic atrophy of the nails 3Inadequate corticosteroid matrix infiltration forCandida paronychiaLichen planus 1OnychotillomaniaPemphigus foliaceusRadiodermatitisRaynaud’s phenomenon 3Sarcoidosis involving the PNFSystemic lupus erythematosusToxic epidermal necrolysisTraumaType 2 lepra reactionresults from trauma is not linked to the intensity ofthe trauma, it may be observed in severe distal injury.Also, pterygium remains exceptional in repeatedchronic trauma inflicted to the PNF in onychotillomania,and we observed one pterygium unguis arisingafter inadequate corticosteroid matrix infiltration forCandida paronychia (Richert, unpublished data, 1997).Ventral PterygiumVentral pterygium (Figure 3) is a newly described conditionin which a distal extension of the hyponychiumanchors to the undersurface of the nail plateand, subsequently, obliterates the distal nail groove.The condition was first described in 1973 by Caputoand Prandi, 5 who coined the term pterygium inversumunguis (PIU) to describe a forward extension ofTable II.Causes of Ventral Pterygium(Pterygium Inversum Unguis)Causalgia of the median nerveCongenital etiologyFamily historyFormaldehyde-containing hardeners 8Lenticular atrophy of the palmar creasesLeprosyNeurofibromatosisParesisScarring in the vicinity of the distal nail grooveSubungual exostosisSystemic connective tissue diseasesSystemic lupus erythematosusSystemic sclerosisthe hyponychium anchoring to the undersurface ofthe nail plate and, thus, obliterating the distal nailgroove.PIU may be either congenital or acquired. Odomet al 6 first described the congenital form as a “congenital,painful and aberrant hyponychium” in 1974.In some instances, PIU has been reported as familialand, in most reported cases, patients sought medicaladvice for the pain or bleeding they experiencedwhen trimming their nails. Causes of PIU are listedin Table II.Because the frequency of ventral pterygium maybe underestimated, especially in asymptomatic cases,Mello Filho 7 performed a systematic digital examinationon 2000 patients and found that 0.4% of theadult population was affected. In these cases there wasno family history, and the condition was observedmore frequently in women than in men. Idiopathicforms were preponderant, and involvement of thetoes remains exceptional.Acquired PIU, which occurs in 16% of patients,is by far the most common form and, though idiopathic,is usually secondary to systemic connectivetissue diseases, progressive systemic sclerosis, and systemiclupus erythematosus. One patient with congenitalPIU developed systemic lupus erythematosusat the age of 19, but whether this was coincidentalVOLUME 66, NOVEMBER 2000 345

PTERYGIUM OF THE NAILCommentsPterygium of the nail has been described on both dorsaland ventral aspects of the nail plate. The dorsalpterygium consists of a forward growth of a projectionof the proximal nail fold that fuses with the underlyingmatrix and, subsequently, with the nail bedand divides the nail plate in 2 lateral segments. Ventralpterygium is a distal extension of the hyponychiumthat anchors to the undersurface of the nailplate and eventually obliterates the distal nail groove.Both conditions are nonspecific abnormalities of thenail apparatus.FIGURE 4. Ventral pterygium of several digits afterapplications of nail polish containing formaldehyde.or related has not been determined.PIU may be secondary to scarring in the vicinityof the distal nail groove, or it may arise from a reactionto formaldehyde-containing nail hardeners 8(Figure 4) or from subungual exostosis. PIU has beenreported once in neurofibromatosis, which was associatedwith lenticular atrophy of the palmar creasesand causalgia of the median nerve. Unilateral PIU ofthe fingers and toes has been reported 1 year after astroke and resulted in paresis of the same side.REFERENCES1. Friedman M. Nagelveranderungen bei lichen ruber. ArchDerm Syph. 1921;135:174-179.2. Zaias N. The nail in lichen planus. Arch Dermatol.1970;101:264-271.3. Edwards EA. Nail changes in functional and organic arterialdisease. New Engl J Med. 1948;239:362-365.4. Tosti A, Piraccini BM, Fanti PA, et al. Idiopathic atrophyof the nails: clinical and pathological study of two cases. Dermatology.1995;190:116-118.5. Caputo R, Prandi G. Pterygium inversum unguis. Arch Dermatol.1973;108:817-818.6. Odom RB, Stein KM, Maibach HI. Congenital, painful,aberrant hyponychium. Arch Dermatol. 1974;110:89-90.7. Mello Filho A. Ocorrencia do “pterygium inversum unguis”em populaçao adulta. Med Cut Ib Lat Am. 1985;13:401-405.8. Daly BM, Johnson M. Pterygium inversum unguis due to nailfortifier. Contact Dermatitis. 1986;15:256-257.DISCLAIMERThe opinions expressed herein are those of the authors and do not necessarily represent the views of the sponsor or its publisher. Please review complete prescribinginformation of specific drugs or combination of drugs, including indications, contraindications, warnings, and adverse effects before administering pharmacologictherapy to patients.FACULTY DISCLOSUREThe Faculty Disclosure Policy of the College of Medicine requires that faculty participating in a CME activity disclose to the audience any relationship with a pharmaceuticalor equipment company that might pose a potential, apparent, or real conflict of interest with regard to their contribution to the program.Drs. Richert, Patki, and Baran report no conflict of interest. Dr. Fisher reports no conflict of interest.346 CUTIS ®