Outbreak of autoimmune disease in silicosis linked to artificial stone

There is a well-established association between inhalational exposure to silica and autoimmune disease. We recently observed an outbreak of silica-related autoimmune disease among synthetic stone construction workers with silicosis referred for lung transplantation assessment.

To characterize the rheumatologic complications in silicosis within these highly exposed, clinically well-characterized patients.

We systematically reviewed data from all cases of silicosis due to synthetic stone dust referred to our pulmonary institute for lung transplant assessment, which represents the national centre for all such referrals. In addition to silicosis-specific data, we extracted data relevant to the clinical and serological manifestations of autoimmune diseases present in these patients.

Of 40 patients in our advanced silicosis national data, we identified nine (23%) with findings consistent with various autoimmune diseases. Among these nine, three also had findings consistent with pulmonary alveolar proteinosis. Based on an expected autoimmune disease prevalence of 3% (based on the upper-end estimate for this group of diseases in European international data), the proportion of disease in our group represents a >7-fold excess (prevalence ratio 7.5; 99% confidence interval 2.6-16.7).

These cases underscore the strong link between silicosis and multiple distinct syndromes of autoimmune diseases. Vigilance is warranted for the recognition of autoimmune complications in persons with known silicosis; so too is consideration of the occupational exposure history in persons presenting with manifestations of autoimmune disease.