Occult paraquat poisoning causing pneumomediastinum and organizing pneumonia.

Pneumomediastinum is not an uncommon manifestation of lung toxicity in acute paraquat ingestion. The condition is almost invariably seen with other lung parenchymal abnormalities such as consolidations, ground-glass opacities and interlobular septal thickening. The diagnosis may be challenging in cases with no history of toxin exposure, presentation with a subacute illness and/or absence of typical local or systemic features of paraquat toxicity.