光化学疗法（ＰＵＶＡ）即补骨脂素长波紫外线照射疗法，是治疗银屑病的一种常用疗法。本文报道３例用光化学疗法治疗银屑病后发生恶性黑色素瘤的病例。３位患者（２男，１女）在初次接受光化学疗法后１２～２０年间分别发生黑色素瘤，他们接受光化学治疗３１～５０１次，... Photochemical therapy (PUVA), which is psoralen long-wave ultraviolet radiation therapy, is a commonly used treatment for psoriasis. This article reports three cases of malignant melanoma after phototherapy in the treatment of psoriasis. Three patients (2 males and 1 female) developed melanoma 12 to 20 years after the initial photochemotherapy. They received photochemical therapy for 31 to 501 times.