A case of sarcoidosis that developed three years after the onset of hard metal asthma.

A 23-year-old man who worked at a hard metal factory from 1988 had developed bronchial asthma in 1990. He was diagnosed as having bronchial asthma by inhalation challenge with cobalt. He never developed a severe attack after that by avoiding inhalation of cobalt. In 1993, he developed iridocyclitis, and his chest radiograph showed bilateral hilar lymph node swelling. He was diagnosed as having sarcoidosis with pathological certainty and an increased serum angiotensin-converting enzyme (ACE) level. On second admission, an inhalational challenge with cobalt resulted in no significant decrease of FEV1. Cobalt is well known to cause occupational asthma and other interstitial lung diseases. Although we could not get clear evidence suggesting an association between the sarcoidosis and his history of cobalt exposure, there is a possibility that changes in the immune reaction to cobalt might explain the improvement of asthma followed by sarcoidosis in this case.