Background: Various types of hyperkeratotic lesions can be observed in patients with psoriasis treated with PUVA. Clinically it can be difficult to classify them and to differentiate benign from malignant hyperkeratotic lesions. Recently, we introduced the term PUVA keratosis, which we regard as a distinct entity.
Objective: The purpose of the study was to describe in more detail the clinical and histopathologic features of PUVA keratoses and to investigate a possible relation with nonmelanoma skin cancer.
Methods: A group of 13 psoriasis patients with PUVA keratoses was studied and compared with 247 psoriasis patients without these keratoses, who had also received long-term therapy with PUVA.
Results: The presence of PUVA keratoses was associated with an increased risk of nonmelanoma skin cancer. The estimated relative risk for skin cancer in patients with PUVA keratoses, adjusted for age, sex, and UVA dose, as compared with psoriasis patients without these keratoses, who had also received long-term PUVA treatment, was 6.5 (95% confidence interval, 1.3 to 32.1). Squamous cell carcinomas contributed the most to this increased risk.
Conclusion: PUVA keratoses are associated with an increased risk of nonmelanoma skin cancer. Therefore careful clinical follow-up of psoriasis patients with PUVA keratoses is necessary, and cessation of PUVA treatment should be considered.