Abstract
Drug-induced interstitial pneumonia results when exposure to drugs results in inflammation, which progresses to fibrosis of the lung interstit-ium. We report on a case of drug-induced interstitial pneumonia caused by Japanese herbal medicine (shini-seihai-to) that was difficult to differentiate from coronavirus disease 2019 (COVID-19) pneumonia due to similarities in clinical features and chest computed tomography (CT) findings. A 72-year-old woman visited a local clinic with complaints of fever and dif-ficulty with breathing and was referred to our hospital because of suspected pneumonia. Chest CT revealed ground-glass and reticular opacity in all lung fields bilaterally. Initially, we suspected COVID-19 pneumonia based on the CT findings and clinical features, but nasopharyngeal swab-based testing and PCR assay for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen were both negative. However, 45 days before ad-mission the patient had been treated for sinusitis with Japanese herbal medicine (shini-seihai-to). Thus, we suspected drug-induced interstitial pneumonia caused by this herbal preparation. Corticosteroid therapy for drug-induced interstitial pneumonia was initiated with prompt improvement. This case highlights the fact that drug-induced interstitial pneumonia, spe-cifically Japanese herbal medicine (shini-seihai-to)-induced interstitial pneumonia, may be considered in the differential diagnosis of COVID-19 pneumonia.
