International Consensus Definition and Diagnostic Criteria for Generalized Pustular Psoriasis From the International Psoriasis Council
Authors: Choon Siew Eng , van de Kerkhof Peter , Gudjonsson Johann E. , de la Cruz Claudia , Barker Jonathan , Morita Akimichi , Romiti Ricardo , Affandi Azura Mohd , Asawanonda Pravit , Burden Arthur David , Gonzalez César , Marrakchi Slaheddine , Mowla Mohammad Rafiqul , Okubo Yukari , Oon Hazel H. , Terui Tadashi , Tsai Tsen-Fang , Callis-Duffin Kristina , Fujita Hideki , Jo Seong Jin , Merola Joseph , Mrowietz Ulrich , Puig Lluïs , Thaçi Diamant , Velásquez Margarita , Augustin Matthias , El Sayed Mahira , Navarini Alexander A. , Pink Andrew , Prinz Jörg , Turki Hamida , Magalhães Renata , Capon Francesca , Bachelez Hervé ,   IPC Pustular Psoriasis Working Group, Aboudourib Maryem , Adji Aryani , Alam Jahangir , Alwakeel Abdelrahman , Bahloul Emna , Barboza da Silva Jaquelini , Barua Deva Pratim , Chiricozzi Andrea , Chularojanamontri Leena , Dadoo Ahmed , de Rie Menno , El-Komy Mohamed , Etemesi Beatrice , Farhana Chowdhury , Gisondi Paolo , Guevara Bryan , Huq Mohammed , JULLIEN Denis , Lambert Jo , Leite Leandro , Mowla Mohammad Rafiqul , Pangastuti Miranti , Reynoso Solange , Silpa-archa Narumol , Torres Tiago , Tumalad Lily Lyralin , Yatsuzuka Kazuki , Yris Taveras Carmen , Yu Yihui , Zhang Xibao 
Published: May 2024

ImportanceGeneralized pustular psoriasis (GPP) lacks internationally accepted definitions and diagnostic criteria, impeding timely diagnosis and treatment and hindering cross-regional clinical and epidemiological study comparisons.ObjectiveTo develop an international consensus definition and diagnostic criteria for GPP using the modified Delphi method.Evidence ReviewThe rarity of GPP presents a challenge in acquiring comprehensive published clinical data necessary for developing standardized definition and criteria. Instead of relying on a literature search, 43 statements that comprehensively addressed the fundamental aspects of the definitions and diagnostic criteria for GPP were formulated based on expert reviews of 64 challenging GPP cases. These statements were presented to a panel of 33 global GPP experts for voting, discussion, and refinements in 2 virtual consensus meetings. Consensus during voting was defined as at least 80% agreement; the definition and diagnostic criteria were accepted by all panelists after voting and in-depth discussion.FindingsIn the first and second modified Delphi round, 30 (91%) and 25 (76%) experts participated. In the initial Delphi round, consensus was achieved for 53% of the statements, leading to the approval of 23 statements that were utilized to develop the proposed definitions and diagnostic criteria for GPP. During the second Delphi round, the final definition established was, “Generalized Pustular Psoriasis is a systemic inflammatory disease characterized by cutaneous erythema and macroscopically visible sterile pustules.” It can occur with or without systemic symptoms, other psoriasis types, and laboratory abnormalities. GPP may manifest as an acute form with widespread pustules or a subacute variant with an annular phenotype. The identified essential criterion was, “Macroscopically visible sterile pustules on erythematous base and not restricted to the acral region or within psoriatic plaques.”Conclusions and RelevanceThe achievement of international consensus on the definition and diagnostic criteria for GPP underscores the importance of collaboration, innovative methodology, and expert engagement to address rare diseases. Although further validation is needed, these criteria can serve as a reference point for clinicians, researchers, and patients, which may contribute to more accurate diagnosis and improved management of GPP.