Risk of cutaneous carcinoma in psoriatic patients treated with PUVA.

A total of 1047 psoriatic patients treated with PUVA were examined for lentiginosis, actinic keratosis and skin cancer. 128 patients had earlier been treated with arsenic, 4 with ionizing radiation and 6 with methotrexate. Lentiginosis was found in 6.2% and actinic keratosis in 1.8% of the patients. 2 patients had histologically verified basal cell carcinoma, 1 had squamous cell carcinoma and 1 Bowen's disease. In patients followed for more than 4 years, those who had received a cumulative dose of UVA greater than or equal to 1000 J/cm2, as well as those who had received more than 150 irradiations had significantly greater frequency of lentiginosis and actinic keratosis. This seemed to be the case also in patients with earlier arsenic treatment. The number of skin malignomas detected did not significantly exceed the expected incidence in the normal Finnish population of the same age-group.