Polymorphous light eruption and benign summer light eruption in Italy

Area of Science:

• Dermatology
• Photobiology
• Immunodermatology

Background:

• Polymorphous light eruption (PLE) is a common photodermatosis with suspected heterogeneity.
• The existence and diagnostic criteria for benign summer light eruption (BSLE), a potentially distinct subtype of PLE, remain controversial.

Purpose of the Study:

• To investigate the prevalence of clinical patterns associated with BSLE.
• To identify criteria that reliably distinguish BSLE from PLE.
• To evaluate the diagnostic utility of phototesting in differentiating these conditions.

Main Methods:

• Retrospective analysis of 346 patients with suspected PLE across five Italian Photodermatology Centres.
• Data collected included patient demographics, skin type, family history, atopy, and clinical presentation.
• Standardized phototesting with UVA and UVB, photopatch testing, and antinuclear antibody (ANA) assessment were performed.

Main Results:

• Applying four specific criteria (female predominance, shorter latency, no facial involvement, no summer relapse) identified BSLE in only 6.1% of cases.
• Patients identified as BSLE consistently showed positive phototests, predominantly to UVA.
• Alternative combinations of criteria identified varying percentages of patients, mostly with positive UVA phototests.

Conclusions:

• Established clinical criteria diagnose BSLE in a small subset of patients presenting with light-induced eruptions.
• Phototesting, particularly with UVA, appears crucial in supporting the diagnosis of BSLE in these selected cases.
• Further research is needed to fully elucidate the distinct characteristics and diagnostic boundaries of BSLE within the spectrum of PLE.