Hypersensitivity pneumonitis associated with inhalation of catechin-rich green tea extracts.

A 51-year-old man presented with fever and fatigue after 3.5 months of antituberculosis therapy. High-resolution computed tomography of his chest revealed new ground-glass opacities and poorly defined centrilobular nodules. He had undergone catechin inhalation for 1 month. We diagnosed hypersensitivity pneumonitis (HP) based on the clinical course, bronchoscopy and a challenge test. Cases of HP due to inhalation of extracted catechin powder are rare. Although it has many known positive attributes, it is necessary to be aware that catechin can cause HP.