Psoralen and Photoactivation

Excerpt

To the editor: The valuable article by Perlman and colleagues, "Photochemotherapy and Psoriatic Arthritis: A Prospective Study" (1), successfully shows that nonspondylitic psoriatic arthritis improves with photochemotherapy. From use of 8-methoxypsoralen and long-wave ultraviolet-A light (PUVA), they conclude that PUVA induces an articular response by improving the psoriasis alone: "Since ultraviolet-A light penetrates only to the dermal layer . . . PUVA therapy presumably has no direct anti-inflammatory effect on joints." The data, however, do not allow such a firm conclusion because a group of patients receiving only 8-methoxypsoralen in the absense of light was not included in the study.