Il fototest iterativo con ultravioletti nella diagnosi di dermatite polimorfa solare: valutazione di 94 casi

Background: polymorphous light eruption (PLE) is a common photosensitivity disorder with an estimated prevalence of 10-20%. It is characterized by non-scarring pruritic erythematous papules, vesicles and/or plaques that develop on light-exposed skin. The principal action spectrum of PLE is mainly in the UVA region, although some subjects exhibit sensitivity to UVB alone or to both UVA and UVB radiation at the same time. Diagnosis is based on clinical history, clinical manifestations and phototest. Objective: the aim of this study was to evaluate the sensitivity of the phototest in patients with a relevant history for PLE. Materials and methods: from December 2003 to September 2005 a total of 94 patients were recruited and all were phototested for the reproduction of skin lesions. The minimal erythema dose (MED) for UVB and an irradiation with UVB and UVA, were administered for five consecutive days. Results: a positive response was seen in 35.1% of this population. The main positive reactions were seen in the areas stimulated with both UVB and UVA (15.9%). The average MED value was similar in all examined patients (73.88 mJ/cm2). Conclusions: although phototesting with UVA and UVB lamps remains a useful method, it is not decisive for the diagnosis of PLE.