Photodynamic therapy of necrobiosis lipoidica--a multicenter study of 18 patients.

BACKGROUND Necrobiosis lipoidica (NL) is a granulomatous skin disease of unknown origin, and no reliably effective treatment option exists to handle this often disfiguring disease. Recently, a patient with long-lasting NL was reported to be cured by topical photodynamic therapy (PDT). OBJECTIVE To evaluate the overall potential of PDT in the treatment of NL on the lower legs. METHODS Retrospective study of 18 patients (aged 16-62 years) from 3 European university departments of dermatology treated with PDT for NL. Methyl aminolevulinate or 5-aminolevulinic acid were used as topically applied photosensitizers. Illumination followed with red light-emitting diode light. RESULTS Complete response was seen in 1/18 patients after 9 PDT cycles, and partial response in 6/18 patients (2-14 PDT cycles) giving an overall response rate of 39% (7/18). CONCLUSION Although almost 40% of the cases showed some degree of response, PDT cannot currently be recommended as first-line therapy of NL. Subpopulations of therapy-resistant NL patients may, however, benefit from PDT.