Hypersensitivity pneumonitis from Pezizia domiciliana. A case of El Niño lung.

A previously healthy woman developed severe dyspnea and was found to have restrictive lung disease and evidence of alveolitis. Open lung biopsy revealed extrinsic allergic alveolitis (hypersensitivity pneumonitis). The etiology was not initially apparent, but a home inspection showed an unusual mushroom growing in the patient's basement. Air sampling and serum precipitins against the fungal antigens confirmed that Pezizia domiciliana was the cause of the patient's hypersensitivity pneumonitis. This is the first described case of hypersensitivity pneumonitis cause by P. domiciliana. We speculate that unprecedented rainfall and flooding of the patient's basement as a result of El Niño rains produced ideal factors for the growth of this fungus.