Actin-containing cells in human pulmonary fibrosis.

Lung tissue from five patients with varying degrees of diffuse pulmonary fibrosis was examined for the presence of nonmuscle cells containing the contractile protein actin. Histochemical studies using light- and electron-microscopic techniques suggested that the fibrotic tissue, in areas lacking smooth muscle, had within it numerous cells with cytoplasmic microfilaments composed of actin. Similar cells rarely were observed in control lung tissue.

Pulmonary pathology in workers exposed to nonasbestiform talc.

We studied pulmonary tissue from seven men employed in the mining and milling of talc that contained minimal amounts of crystalline silica and asbestiform minerals. The lungs exhibited varying degrees of fibrosis, located either adjacent to the vessels and bronchi or diffusely. Semiquantitative estimations of talc in the lung tissue indicated that the extent of the pulmonary lesions corresponded to its concentration in the tissue.

Electron-probe microanalysis. Aid in the study of skin granulomas.

Several causes of noncaseating epithelioid granulomas of the skin must be considered before the diagnosis of sarcoidosis can be made. We report here three such cases that were studied retrospectively with scanning electron microscopy in combination with backscattered electron imaging and x-ray energy spectrometry. Inorganic particles were identified in the granulomas of two patients, illustrating that these techniques are valuable aids in establishing the cause of granulomas.

Cryptic pulmonary lesions in workers occupationally exposed to dust containing silica.

Fibrotic lesions associated with deposits of crystalline silica were found postmortem in the lungs of 15 granite workers who lacked radiological evidence of pneumoconiosis. All members of this occupational group had been employed in the granite quarrying and monument industry of Vermont since ambient air-dust standards were introduced in 1937. Although particulate silica was not revealed in the lesions by traditional polarization light microscopy, it was identified by scanning electron microscopy in conjunction with backscatter imaging and x-ray spectrometry.