Hypersensitivity pneumonitis induced by Shiitake mushroom spores

Hypersensitivity pneumonitis due to the inhalation of Shiitake mushroom spores was demonstrated in a 38-year-old woman. Symptoms of cough, nausea and malaise, and clinical findings of cyanosis, bibasilar crackles, reduced lung volumes, hypoxemia, leukocytosis, elevated ESR, positive C-reactive protein, and bilateral diffuse reticulonodular shadows on chest roentgenogram improved after the patient was removed from exposure. Alveolitis was demonstrated by transbronchial lung biopsy, as well as an increase in lymphocytes in bronchoalveolar lavage. Serum precipitins and specific IgG antibodies to an extract of Shiitake mushroom spores, but not to other common molds or mushroom body, were detected in serum. Provocative inhalation test with the extract of mushroom spores caused the same clinical symptoms and signs as experienced in the workroom. This is the first report of typical hypersensitivity pneumonitis induced by Shiitake mushroom spores. Mushroom spores as well as thermophilic actinomycetes must be considered a causative agents for mushroom worker's lung.