Woronoff's rings with PUVA therapy.

To the Editor.— We were interested in the report by Lowe and Bures on the occurrence of Woronoff's rings (WR) in patients with psoriasis who were undergoing psoralen and ultraviolet A (PUVA) treatment (Archives114:278-279, 1978). Penneys and his colleagues1have suggested that an inhibitor of prostaglandin (PG) synthesis diffuses outward from psoriatic plaques and inhibits PGE2formation in WR. We have reported that UVB-(300 nm) induced erythema in man is associated with increased levels of PGE, and PGF2α.2Lowe and Bures cite the work of Lord et al,3who reported that PG biosynthesis was stimulated by methoxsalen and UVA irradiation (360 nm). They then conclude that if the WR are induced by the inhibition of PG synthesis, the occurrence of WR in PUVA-treated skin implies that the photosensitization from PUVA results from increased PG synthesis. They refer to an article by Morrison et al,4