European consensus statement on phenotypes of pustular psoriasis

Pustularpsoriasis (PP) isagroupof inflammatoryskinconditionscharacterizedby infiltrationofneutrophil granulocytes in theepidermis tosuchanextent that clinicallyvisiblesterilepustulesdevelop.Becauseof clinical co-incidence, PP is currently groupedwith psoriasis vulgaris (PV). However, PP andPV are phenotypically different, responddifferently totreatmentsandseemtobedistinctonthegenetic level. Incontrast toPV, thephenotypesof PParenotwell defined.Descriptionsof each formof PParediscordant amongstandarddermatology textbooks [SauratDermatologie2016, Rook’sDermatology2016, Fitzpatrick’s2012andBraun-Falco2012], encumbering the collectionofphenotypicallywell-matchedgroupsofpatientsaswellasclinical trials.TheEuropeanRareandSevere PsoriasisExpertNetwork(ERASPEN)wasfoundedtodefineconsensuscriteriafordiagnosis,deeplyphenotypelarge groupsofPPpatients,analysethegeneticsandpathophysiologyandprepareforprospectiveclinical trials.Thiswork reviewshistorical aspectsof theseconditions, newgeneticfindingsandpresentsour initial considerationson the phenotypesofPPandaconsensusclassificationof clinical phenotypes thatwill beusedasabaseline for further, prospectivestudiesofPP.Generalizedpustularpsoriasis(GPP) isdefinedasprimary,sterile,macroscopicallyvisible pustulesonnon-acralskin(excludingcaseswherepustulationisrestrictedtopsoriaticplaques).GPPcanoccurwith or without systemic inflammation, with or without PV and can either be a relapsing (>1 episode) or persistent (>3months) condition. Acrodermatitis continua of Hallopeau (ACH) is characterized by primary, persistent (>3months), sterile,macroscopicallyvisiblepustulesaffectingthenail apparatus.Palmoplantarpustulosis (PPP) has primary, persistent (>3months), sterile,macroscopicallyvisiblepustulesonpalmsand/or solesandcanoccurwith orwithoutPV.