Clinicopathological features of chronic hypersensitivity pneunionitis

Objective: Only limited information exists concerning the clinical and pathological features of chronic hypersensitivity pneumonitis (HP) in Japan and elsewhere. We present data on clinicopathological features of chronic HP obtained through a Japanese nationwide survey. Methodology: We studied the clinical and pathological findings in 10 patients with chronic HP who underwent surgical lung biopsy or postmortem examination. Results: There were three types of clinical course: six of the 10 patients had persistent symptoms followed by repeated acute episodes; two showed a subacute onset with persistent symptoms; and two exhibited an insidious onset. Five patients made no attempt to avoid antigen exposure and they all had progressive disease. Pathological findings indicated that lesions were mainly centrilobular with or without epithelioid cell granulomas in specimens obtained during the acute or subacute stage. In contrast, most patients in the chronic stage predominantly showed interstitial fibrosis with a usual interstitial pneumonia pattern. Conclusions: The pathological findings of chronic HP depend on the stage of the disease at tissue sampling.