X-ray microanalysis of peripheral lung carcinomas.

A total of 15 cases of peripherally located lung carcinomas associated with scar (scar carcinoma) were studied by light microscopy and electron microscopy with energy-dispersive X-ray microanalysis (XMA). Results were compared to those of three autopsy lungs without significant pulmonary findings that served as controls. Fibrosis with scar formation characterized the 15 tumor cases. Particulate depositions including doubly refractile particles were also increased in the tumor group. XMA identified 25 elements with great complexity of particulate composition. Silicon was the most prominent element and was found in 16 of 18 cases studied. Kaolinite, feldspar, talc, muscovite, and silica were recognized. The fibrogenic properties of silicate compounds were emphasized, including their prominence in the lung tumor group. While the important concept of tumor desmoplasia was recognized, the study showed significant fibrosis in relation to fibrogenic materials, which undoubtedly preceded the appearance of the tumors. Also noted were the carcinogens uranium, cadmium, chromium, nickel, and arsenic, some of which were previously described as minor constituents of naturally occurring minerals.