A Case of Acetaminophen-induced Pneumonitis

Abstract

A case of acetaminophen-induced pneumonitis is described. A 63-year-old woman took 2350mg of acetaminophen for fever. She subsequently developed a non-productive cough and dyspnea. Chest X-ray revealed diffuse reticulonodular shadows in bilateral lung field and she was admitted to our hospital. PaO₂ was 45.0Torr and PaCO₂ 35.7Torr while breathing room air. Bronchoalveolar lavage examination showed an increase in the percentage of lymphocytes and a decrease of CD4/CD8 ratio. Microscopic examination of a transbronchial lung biopsy specimen showed alveolar septal thickening. The lymphocyte stimulation test was positive for acetaminophen, with a stimulation index of 237%, while other drugs used were negative.
Because drug-induced pneumonitis was suspected, all drugs were stopped and she was administered methylprednisolone. Consequently her symptoms, laboratory data and chest X-ray findings improved. Based on these findings, we diagnosed this case as acetaminophen-induced pneumonitis. To our knowledge, there has been only one previously reported case of acetaminophen-induced pneumonitis.