Dermoscopic Changes of Melanocytic Nevi after Psoralen-Ultraviolet A and Narrow-Band Ultraviolet B Phototherapy

BACKGROUND: Phototherapy may alter the morphologic features of melanocytic nevi. Dermoscopy is a non-invasive method for evaluation of skin lesions, specifically melanocytic nevi. AIMS AND OBJECTIVES: This study was designed to evaluate the effects of narrowband ultraviolet B (NB-UVB) and psoralen-ultraviolet A (PUVA) therapy on the dermoscopic features of nevi. METHODS: A total of 74 melanocytic nevi were randomly selected from 20 patients. Out of those, 54 nevi received NB-UVB, while 20 received PUVA. 50% of the nevi in each group were exposed to radiation, while the remaining nevi were covered with an opaque tape. All nevi were demoscopically evaluated before and after 30 or 60 sessions of phototherapy. RESULTS: Overall demoscopic changes were observed in 34/37 (91.8%) of the uncovered nevi compared to 16/37 (43.2%) of the covered nevi (P value 0.0001). The most common changes were new dot/globule formation (62.1%), darkening (32.4%), nevus enlargement (27%), and patchy pigmentation (18.8%). Compared to NB-UVB, dermoscopic changes were more frequent in both covered and uncovered nevi of the PUVA group. (P values 0.041 and 0.0172, respectively). New dot/globule formation was observed more frequently in the covered and uncovered nevi of PUVA group. CONCLUSION: PUVA and NB-UVB induce dermoscopic changes in the majority of the irradiated nevi. However, PUVA is associated with higher frequency of dermoscopic changes in both covered and uncovered nevi.