Identification of mineral particles in pneumoconiotic lungs.

An extraction replication technique has been used for the study, by electron microscopy, of lung tissue from a number of different cases of pneumoconiosis. The technique provides a relatively simple means of studying the surface area of replicated tissues, and any foreign particles present which are either replicated or extracted from the tissue can be identified. A set of standard micrographs of different types of mineral particles likely to be encountered should be kept for reference. Most of the particles identified by this technique were beyond the limits of resolution of optical microscopy. Furthermore, the procedure involves the minimum of chemical and physical treatment. The histochemical diagnosis and industrial history was confirmed in the first two cases described, by the electron microscopy investigations. The third case presented an uncertain histological and industrial history, but an electron microscopy study confirmed the presence of the mineral particle considered responsible for the clinical condition. The fourth and fifth cases described illustrate the use of this technique in identifying a particular type of pleomorphic mineral, and illustrating its position in situ in relation to surrounding tissue.