Pneumomediastinum caused by occult paraquat poisoning Case report

Rationale: Paraquat is a widely applied contact herbicide that is highly poisonous. About 20% of patients with paraquat poisoning develop pneumomediastinum as a complication with a mortality rate of almost 100%. Patient concerns: A 15-year-old boy presented with a 1-month history of retrosternal chest pain with no obvious cause. High resolution computed tomography showed pneumomediastinum. Diagnoses: After all likely causes of pneumomediastinum were eliminated, the diagnosis of occult paraquat poisoning was made when serum paraquat concentration was revealed at 467.40 ng/mL: despite the patient's denial of ingestion or contact. Interventions: Hemoperfusion, intravenous glucocorticoid, and ulinastatin was administered for 3 days with other routine treatment against paraquat poisoning. The serum paraquat concentration decreased to zero. Outcomes: Despite the general high mortality and poor prognosis of paraquat poisoning, the patient recovered and was completely asymptomatic at his 3-month follow-up. Lessons: Paraquat poisoning should be suspected as a differential diagnosis when patients present with pneumomediastinum without recognizable cause.