[A case of bird related hypersensitivity pneumonitis had a progressive course].
A 50-year-old woman was admitted due to productive cough continuing for 3 years. A chest computed tomography showed appearance of nonspecific interstitial pneumonia (NSIP). Thoracoscopic lung biopsy specimens showed mainly a pattern of NSIP with multinucleated cells and cholesterol clefts. She was not a bird fancier, but had indirect exposure to birds in her living environment, and had been using feather-filled duvets for a long time. We established a diagnosis of bird-related hypersensitivity pneumonitis based on antibodies in serum positive to pigeon dropping extracts. She was treated by coadministration of corticosteroids and immunosuppressants, and avoidance of bird-related antigens, but had a progressive course and died of respiratory failure.