[Pneumoconiosis due to amorphous silica smoke. Mineralogical and ultrastructural study of 6 cases (author's transl)].

Pneumoconiosis was diagnosed in 10 patients working in a silicon factory. The exposure time varied between seven and thirty-five years. All patients had only slight or no symptoms, except one presenting an important dyspnea. The radiologic study showed an interstitial syndrome. The functional lung test revealed a restrictive syndrome. Seven patients underwent fibroscopy with alveolar washing and transbronchial biopsy. A surgical biopsy was performed in two patients. The histological lesions showed an accumulation of alveolar and interstitial macrophages and the existence of fibrous interstitial micronodules. The ultrastructural study revealed an interstitial fibrosis. The macrophages contained numerous dense, homogenous small spheres of amorphous structure, composed of silicon and oxygen. These spheres represent amorphous silica smoke particles. Less than 1% of the particles are crystalline silica. Thus, the amorphous silica particles seem to be responsible for the histological and radiological lesions observed.