RESUMO
Pityriasis lichenoides chronica (PLC) is an infrequent dermatosis of unknown aetiology, wholse evolution and response to treatment differs between children and adults. When PLC is recalcitrant or unresponsive to topical treatment, phototherapy is one of the main treatments used. We carried out a prospective study of adult diffuse PLC treated with narrowband ultraviolet B (NB-UVB). We treated eight patients whose disease showed no response to topical therapy, and obtained a complete response rate of 88% in a mean of 23 sessions (cumulative dose 16.99 J/cm2 ). However, the relapse rate was 43% in the first 6 months. Our results are similar to those of other published studies but there is much variability between them in the doses applied and the number of sessions needed. Further studies are necessary to devise a protocol for NB-UVB treatment of PLC.