[Chronic hypersensitivity pneumonitis induced by Shiitake mushroom cultivation: case report and review of literature].

A 72-year-old man, a Shiitake mushroom grower over fifty years, was admitted to our hospital because of bilateral chest interstitial shadow with chronic cough and breathlessness. Chest computed tomography showed traction bronchiectasis, subpleural micro-cystic changes and partial ground-glass opacities in both lungs, and mild mediastinal lymphadenopathy. A diagnosis of chronic hypersensitivity pneumonitis induced by Shiitake mushrooms was comprehensively confirmed by occupational history, radiological findings, and positive findings of an incidental environmental provocation test and lymphocyte stimulation test for Shiitake mushroom extracts. We reviewed the clinical features in five patients with chronic hypersensitivity pneumonitis induced by Shiitake mushrooms reported in Japan. There was a tendency toward increasing lymphocytes and high CD4/CD8 ratio in bronchoalveolar lavage fluids. Treatment with steroids seems to have a limited effect, while avoidance of the antigen is important.