The goal of this observational registry study is to characterize the clinical, epidemiological, and therapeutic features of patients with generalized pustular psoriasis (GPP) in Costa Rica through a standardized national registry. The main question it aims to answer is:

What are the clinical, epidemiological, and therapeutic characteristics of patients with generalized pustular psoriasis registered in the country, and how do these relate to disease severity and evolution?

Patients with GPP receiving routine dermatologic care in participating centers will have their demographic, clinical, severity, comorbidity, and treatment data recorded using a standardized case report form. Clinical assessments (e.g., GPPASI, PASI/BSA, DLQI), laboratory results, triggers, complications, and therapies will be documented and updated during periodic follow-up visits as part of usual care.

Generalized pustular psoriasis (GPP) is a rare, severe, and potentially life-threatening inflammatory dermatosis characterized by recurrent flares of sterile pustules on erythematous skin with systemic involvement. In Costa Rica and much of Latin America, the absence of structured epidemiologic and clinical data has limited understanding of disease burden, phenotypic patterns, triggers, comorbidities, and real-world therapeutic outcomes. This has contributed to diagnostic delays, heterogeneous management, and uncertainty regarding optimal use of systemic and biologic therapies.

To address this gap, a national observational registry has been established within the Costa Rican Social Security health system to systematically collect standardized longitudinal data on patients with confirmed GPP. The registry captures information generated during routine dermatologic care without altering clinical management. Data are entered in a structured case report form aligned with international GPP research standards and include demographics, clinical phenotype, disease course, severity indices (e.g., GPPASI, PASI/BSA, DLQI), laboratory markers, comorbidities, identified triggers, and details of systemic and biologic treatments and their outcomes. Periodic follow-up enables evaluation of disease evolution, treatment persistence, dose modifications, adverse events, and complications over time.

The registry is designed to generate the first national dataset on GPP, enabling characterization of prevalence, regional distribution, severity patterns, and therapeutic responses in the local population. Standardized data collection is expected to improve comparability across centers, support development of evidence-based national management strategies, and facilitate participation in international collaborative research networks focused on rare and severe psoriasis.

Inclusion Criteria:

• Confirmed diagnosis of generalized pustular psoriasis (GPP) established by a board-certified dermatologist based on compatible clinical and/or histopathologic criteria.
• Registered diagnosis of GPP in the institutional electronic health record system (EDUS code L401) during the study period.
• Patients of any age and sex receiving care within participating centers of the Costa Rican Social Security system.
• Availability of clinical information sufficient for registry data entry and follow-up according to routine care.

Exclusion Criteria:

• Patients without a confirmed diagnosis of generalized pustular psoriasis (GPP) or with alternative pustular dermatoses (e.g., acute generalized exanthematous pustulosis) not meeting GPP diagnostic criteria.
• Absence of verifiable diagnosis in the institutional electronic health record (EDUS) or insufficient documentation to confirm GPP.
• Patients whose clinical records lack the minimum data required for registry variables or follow-up within routine care.

All

The study population comprises patients of any age and sex with a confirmed diagnosis of generalized pustular psoriasis (GPP) receiving routine dermatologic care within participating centers of the Costa Rican Social Security (CCSS) health system. Eligible individuals are identified through the institutional electronic health record (EDUS) and enrolled in the national GPP registry during the study period. The population reflects real-world clinical practice across tertiary and regional referral hospitals, including both prevalent and incident GPP cases with varying disease duration, severity, comorbidity profiles, and exposure to conventional systemic and biologic therapies. Data are derived exclusively from standard clinical evaluations and follow-up visits conducted as part of usual care.

According to protocol