Case Report: Pulmonary alveolar proteinosis and fibrosis associated with indium-tin-oxide exposure

Pulmonary alveolar proteinosis (PAP) is a rare respiratory disorder characterized by the excessive accumulation of surfactant material on alveolar surfaces and the dysfunction of alveolar macrophages. Indium-tin-oxide (ITO), a substance utilized in liquid crystal displays and solar panels, could be a potential cause of secondary PAP. Here, we report a rare case of interstitial lung disease in a solar panel processing worker with ITO exposure, which was pathologically confirmed as PAP and then progressed to pulmonary fibrosis.

A 35-year-old male was admitted with a symptom of dysponea. Chest computed tomography revealed diffuse, bilateral ground-glass opacities and interlobular septal thickening in both lungs. Transbronchial lung biopsy was PAS-positive, confirming the diagnosis of PAP. The indium levels in the patient's bronchoalveolar lavage fluid and plasma were far above the normal range. He underwent whole-lung lavage, but approximately 4 months later, he still developed progressive pulmonary fibrosis. Nintedanib showed no significant effect in slowing the decline of his lung function.

When a patient has a definite history of indium exposure, the diagnosis of PAP should be considered. Workers need to wear protective measures daily, as lung diseases caused by ITO exposure are associated with a poor prognosis.