Allergic reaction to benzophenone. Simultaneous occurrence of urticarial and contact sensitivities

A black man with a broad-spectrum light sensitivity simultaneously showed an urticarial and contact sensitivity to a preparation containing 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (sulisobenzone). Both the benzophenone and sulfonic acid parts of the molecule were required for elicitation of the contact reaction, while benzophenone alone elicited the urticarial reaction.