Narrowband UVB phototherapy for skin diseases such as psoriasis is an effective and safe treatment modality. However, the possibility of increasing the risk of skin cancer and lentigines caused by phototherapy is a serious concern. In contrast, the role of narrowband UVB therapy in skin carcinogenesis and lentigines is less clear. We investigated the incidence of skin tumors and lentigines in a total of 62 patients receiving narrowband UVB therapy between December 1999 and April 2005. The median cumulative term of the narrowband UVB treatment and the total dose were 22.3 months (range, 7–53) and 92.3 J/cm
2 (14.4–552.5), respectively. The risk of skin cancer was not increased after the treatment. Lentigines were observed in 17 (27.4%) out of the 62 patients. However, we found that, of these 17 patients, 14 (82.4%) had undergone another type of phototherapy, and 9 (52.9%) had a long history of much sunbathing. Subsequently, out of the 62 patients, 30 patients received only the narrowband UVB therapy without any other phototherapies, and lentigines were observed in only 3 of those patients. To determine the true long-term risk of the narrowband UVB phototherapy, longer follow-up observations are required in a number of patients with only this exposure.
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