European consensus statement on phenotypes of pustular psoriasis

Area of Science:

• Dermatology
• Immunology
• Genetics

Background:

• Pustular psoriasis (PP) is characterized by sterile pustules due to neutrophil infiltration, clinically grouped with psoriasis vulgaris (PV).
• PP and PV exhibit distinct phenotypes, treatment responses, and genetic underpinnings, necessitating clearer PP classification.
• Current PP phenotype descriptions are inconsistent across major dermatology textbooks, hindering research and clinical trial patient cohorting.

Purpose of the Study:

• To establish consensus criteria for diagnosing PP and deeply phenotyping patient groups.
• To analyze the genetics and pathophysiology of PP.
• To propose a consensus classification of clinical PP phenotypes for future studies.

Main Methods:

• Review of historical aspects and recent genetic findings related to PP.
• Development of a consensus classification for clinical PP phenotypes.
• Definition of specific PP subtypes: Generalized Pustular Psoriasis (GPP), Acrodermatitis Continua of Hallopeau (ACH), and Palmoplantar Pustulosis (PPP).

Main Results:

• Generalized Pustular Psoriasis (GPP) defined by sterile pustules on non-acral skin, with or without systemic inflammation or PV.
• Acrodermatitis Continua of Hallopeau (ACH) characterized by persistent sterile pustules affecting the nail apparatus.
• Palmoplantar Pustulosis (PPP) defined by persistent sterile pustules on palms/soles, with or without PV.

Conclusions:

• PP represents a distinct group of inflammatory skin conditions separate from PV.
• A consensus classification of PP phenotypes is crucial for advancing research and clinical trials.
• Standardized definitions will facilitate better understanding and management of diverse PP presentations.