A case report of an indium lung with progressive emphysema and fibrosis that underwent unilateral lung transplantation 20 years after the end of the exposure

Abstract Background: Indium lung is characterized by interstitial pneumonia and/or emphysema, which occurs in indium-tin oxide (ITO) workers. Indium lung is now known to progress after stopping exposure to ITO, but the long-term influences of ITO remain unclear. Case presentation: A 47-year-old, male never-smoker, who was engaged in an ITO manufacturing process for 8 years. Emphysema was indicated by a medical check-up for ex-ITO workers, and the subject was diagnosed with indium lung. He underwent partial lung resections for pneumothorax twice, and obstructive pulmonary dysfunction progressed over the years. The subject underwent right single lung transplantation 20 years after ITO exposure. Pathologically, his lung showed severe distal acinar emphysema and honeycomb change. Fibrosis and destruction of the lung tissue significantly progressed compared to the previous partial resections. Scanning electron microscopy combined with energy dispersive spectroscopy revealed that the deposited particles contained indium and tin. After transplantation, his respiratory function was improved. Conclusions: In this case, ITO resided in the lung tissue for 20 years, and lung tissue destruction continued to progress. Careful medical follow-up is recommended for ITO workers even if they are asymptomatic.