Photopatch testing in Bogota (Colombia): 2011-2013

Area of Science:

• Dermatology
• Allergology
• Photodermatology

Background:

• Photopatch testing is essential for diagnosing photoallergic contact dermatitis (PACD) and identifying causative agents.
• Allergen prevalence and positive test frequencies vary geographically, necessitating country-specific data.
• Understanding local patterns of PACD is crucial for accurate diagnosis and management.

Purpose of the Study:

• To determine the frequency and relevance of positive photopatch test results in Colombian patients with suspected PACD.
• To identify common allergens responsible for PACD in Bogota, Colombia.
• To contribute country-specific data to the global understanding of PACD epidemiology.

Main Methods:

• A cohort of 100 patients with suspected PACD underwent photopatch testing.
• Standardized testing involved occlusion, UVA irradiation (5 J/cm²), and readings on days 2, 4, and 6.
• Relevance of reactions was assessed using the COADEX system.

Main Results:

• Fifteen patients (15%) showed 20 positive photopatch reactions.
• UV filters were the primary cause (95%), with benzophenone-3 being the most frequent allergen (55%).
• Delayed reactions were common, with 53.3% of positive results appearing on day 6.

Conclusions:

• UV filters remain the leading cause of PACD in the studied Colombian population.
• Extended reading times up to day 6 (96 hours post-irradiation) are vital for detecting delayed hypersensitivity reactions.
• These findings underscore the importance of country-specific data for diagnosing and managing PACD.