Pseudodiphtheria: prominent pharyngeal membrane associated with fatal paraquat ingestion.

Three patients presented with prominent pharyngeal membranes suggestive of tonsillar-pharyngeal diphtheria, but later found to be caused by oral ingestion of the herbicide paraquat. In all cases appropriate therapy was delayed because of failure to include paraquat in the differential diagnosis: Paraquat ingestion should be considered in all patients with prominent tongue and pharyngeal membranes.