[A case of rapid development of arc welder's lung during the course of a year]

A 57-year-old man who had worked as a welder for about 40 years was admitted to our hospital. Every year he had had medical examinations in his workplace. On March 17, 1999, there was no finding of pneumoconiosis, but he had worked in a tunnel on a special arc welding project from December 20, 1999 to January 10, 2000. On admission, chest radiography revealed reticular shadows in the middle and lower lung fields. CT scans showed ground-glass opacities in both lungs. Serum iron was high (231 micrograms/dl) and serum ferritin was extremely high (2,309 ng/ml). Many iron particles were detected in the alveoli of the transbronchial biopsy specimen, and also in the sputum. A pathological diagnosis of siderosis was therefore made, and, considering the patient's occupation, the condition was termed arc welder's lung. This rapidly developing case was characterized by reticular shadows on chest radiography.