Table 2.

Published GPP diagnostic criteria

ERASPEN [1]	JDA [2]
Primary, sterile, macroscopically visible pustules on non-acral skin (excluding cases in which pustulation is restricted to psoriatic plaques) With or without systemic inflammation With or without plaque psoriasis Relapsing (> 1 episode) or persistent (> 3 months)	(i) Systemic symptoms such as fever and fatigue (ii) Systemic or extensive flush accompanied by multiple sterile pustules that sometimes merge to form lakes of pus (iii) Neutrophilic subcorneal pustules histopathologically characterised by Kogoj’s spongiform pustules (iv) Repeated occurrence of these clinical and histological features
GPP should only be diagnosed when the condition has relapsed at least once or when it persists for more than 3 months	Definitive GPP diagnosis if all four parameters are met; suspected GPP diagnosis if parameters (ii) and (iii) are met

ERASPEN European Rare and Severe Psoriasis Expert Network, GPP generalized pustular psoriasis, JDA Japanese Dermatological Association