Therapeutic effects for hypersensitivity pneumonitis induced by Japanese mushroom (Bunashimeji)

Bunashimeji-related hypersensitivity pneumonitis is found among workers who cultivate the mushroom in indoor facilities. An evaluation of protective measures was initiated using the outcomes of clinical, immunological, and radiological findings.

Twenty-two patients presented with symptoms of HP; all were employed cultivating Bunashimeji mushrooms in indoor facilities. After hospitalization, 6 of 22 patients quit their job to avoid exposure to spores (Avoidance group). Sixteen patients continued to work used a mask for 3 months, and were then divided into two subgroups: Mask alone (seven patients) and mask plus oral prednisolone (Mask + PSL) (nine patients). The erythrocyte sedimentation rate (ESR), serum Krebs von der Lungen-6 (KL-6), surfactant protein-D (SP-D), lymphocyte stimulation test (LST), ground-glass scores in chest high-resolution computed tomography (HRCT), and bronchoalveolar lavage (BAL) were assessed before and after treatment.

Complete avoidance resulted in a significant decrease in LST. There was a significant decrease after PSL treatment in serum KL-6, SP-D, and total cell counts in the BAL fluid in the Mask + PSL group. In the Mask alone group, serum KL-6, SP-D, ground-glass scores in chest HRCT and total cell counts in BAL fluid showed high levels compared with the other two groups.

Complete cessation was the best treatment for hypersensitivity pneumonitis. The use of a mask was ineffective for patients with a high serum KL-6 and SP-D concentration and severe ground-glass opacity on chest HRCT. Initial treatment with PSL is recommended for these patients with high levels of total cell counts in BAL fluid.