Pneumonitis due to Hangeshashin-to

A 72-year-old woman was admitted to our hospital because of dyspnea and abnormal shadows on a chest X-ray film. The X-ray film revealed diffuse reticular and patchy shadows in both lung fields. Drug-induced pneumonitis was suspected, and all drug treatment was stopped. The symptoms were relieved and the X-ray findings improved markedly. In bronchoalveolar lavage fluid, the lymphocyte percentage was high and the CD4/CD8 ratio was low. Microscopic examination of open-lung biopsy specimens showed pneumonitis, dominant lymphocyte invasion within peribronchiolar and alveolar interstitia. The result of leukocyte migration inhibition test was positive for Hangeshashin-to and Byakkokaninjin-to, and lymphocyte stimulation test was positive for Hange, an ingredient of Hangeshashin-to. Based on these findings, we diagnosed as pneumonitis induced by Hangeshashin-to. To our knowledge, there has been no previous report of pulmonary hypersensitivity induced by Hangeshashin-to in Japan.