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Updated: Aug 18, 2026

Minimal Erythema Dose (MED) Testing
Published on: May 28, 2013
Clinical and therapeutic aspects of polymorphous light eruption
Reinhard Dummer1, Katya Ivanova, E Paul Scheidegger
1Department of Dermatology, University Hospital, Zurich, Switzerland. reinhard.dummer@der.usz.ch
Background:
Polymorphous light eruption (PLE) is an idiopathic eruption induced by ultraviolet (UV) radiation (UVR).
Objective:
Evaluation of the clinical aspects, diagnostic criteria of PLE in a major Swiss referral center.
Methods:
25 patients with PLE were tested with a standardized protocol for the assessment of photodermatoses.
Results:
25 patients (22 women vs. 3 men) were identified. Papular and papular-vesicular eruptions were the most common clinical presentations. 6 of 25 patients had a reduced minimal erythema dose (MED) for UVA and 8 of 25 patients had a reduced MED for UVB. Photoprovocation was positive in 11 of 20 patients for UVA and 7 of 20 patients for UVB. Photohardening with narrow-band UVB was successful in 8 of 10 patients. Combined UVA/UVB therapy had a satisfactory effect in 10 of 15 patients. Narrow-band UVB therapy was still successful after ineffective UVA/UVB therapy.
Conclusion:
The MED was of no value for the diagnosis of PLE. The typical lesions were reproduced by UVA and UVB photoprovocation. We recommend photohardening with narrow-band UVB (311 nm).
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