Silicosis caused by chronic inhalation of snail shell powder.

A 70-yr-old woman visited our hospital for shortness of breath. Chest CT showed ground glass opacity and traction bronchiectasis at right middle, lower lobe and left lingular division. Video-assisted thoracic surgical biopsy at right lower lobe and pathologic examination revealed mixed dust pneumoconiosis. Polarized optical microscopy showed lung lesions were consisted of silica and carbon materials. She was a housewife and never been exposed to silica dusts occupationally. She has taken freshwater snails as a health-promoting food for 40 yr and ground shell powder was piled up on her backyard where she spent day-time. Energy dispersive X-ray spectroscopy of snail shell and scanning electron microscopy with energy dispersive x-ray spectroscopy of lung lesion revealed that silica occupies important portion. Herein, we report the first known case of silicosis due to chronic inhalation of shell powder of freshwater snail.