Hypersensitivity pneumonitis induced by Shiitake mushroom spores.

Hypersensitivity pneumonitis (HP) is a pulmonary granulomatosis involving an immunoallergic mechanism caused by chronic inhalation of antigens, most frequently organic substances, as well as chemicals. We report the first European case of hypersensitivity pneumonitis due to the inhalation of Shiitake mushroom spores. A 37-year-old French Caucasian man with a one-month history of persistent dry cough, shortness of breath and loss of weight was admitted to our hospital on December 2010. Anamnesis showed he was involved in mushroom production beginning in the summer of 2010. His temperature on admission was 36.6°C and he had a normal blood pressure (135/90 mmHg). Bilateral fine crackles were audible in the base of both lungs. Pulmonary function tests showed a mild restrictive pattern with decreased DLco and a PaO(2) of 65 mmHg, Chest CT scan revealed reticulo-nodular shadows, slight ground glass opacities, liner atelectasis, and subpleural opacities in both lung fields. Bronchoscopy was normal but cytological examination of BAL revealed a predominant lymphocytosis (55%). Serum precipitins to the Shiitake mushroom spores were positive (3 precipitins arcs with high intensity) and as a result we advised the patient to cease his mushroom production activities. The diagnosis of hypersensitivity pneumonitis due to inhalation of Shiitake mushroom spores was established as a result of the improvement of all of his clinical symptoms, i.e., cough, weight loss, bilateral fine crackles, mild restrictive pattern of pulmonary function, and reticulo-nodular shadows on chest CT, once exposure was eliminated. Recent interest in exotic mushrooms varieties, e.g., Shiitake, in developed countries because of their possible medicinal properties might increase the potential risk of HP among mushrooms workers. Therefore, healthcare professionals have to take this new potential respiratory disease into account.