Wandering fixed drug eruption: a mucocutaneous reaction to acetaminophen

Two patients are presented with a fixed drug eruption to acetaminophen characterized by recurring erythematous, circular plaques of the skin and oral mucosa along with multiple sites of deep (postinflammatory) hyperpigmentation clinically characteristic of fixed drug eruption. The involved sites did not necessarily flare with each exposure, nor did activity always appear in the same sites with each flare. Eventually some sites apparently became completely refractory. This caused the eruption to seem to "wander." Patch testing with 1% acetaminophen in alcohol (300 mg/30 ml alcohol) confirmed the causative agent in one patient. Although patch testing was negative in the other patient, oral reexposure caused a flare. Acetaminophen appears to be an uncommon cause of fixed drug eruption, with a tendency for lesions to appear at the same or at different sites in flares, perhaps because of a prolonged refractory period and the tendency to become completely refractory in some locations.