[Quartz crystals in the skin as a cause of progressive systemic scleroderma].

There is a close correlation between the systemic sclerosis and the exposure to crystalline silica in the GDR. The silica content was investigated in the skin of the patients. Silica particles were found using phase-contrast and polarizing microscopy. The size of the crystals varied from 1 to 90 micrometer. Below a silica content of 10% in the dust it is unlikely that systemic sclerosis is developing.