A Broader Concept of Caplan's Syndrome Related to Rheumatoid Factors

The rheumatoid pneumoconiosis syndrome was originally described as a characteristic chest radio- graphic appearance in coal-workers associated with clinical rheumatoid arthritis This association was later confirmed as real and not fortuitous by Miall, Caplan, Cochrane, Kilpatrick, and Oldham (1953) using an unselected population. The original communication defined the radio- graphic picture as one showing multiple, well- defined round opacities 0.5 to 5 cm. in diameter distributed throughout the lung field. We will call this the classical appearance. It was noted that cavitation and calcification of the opacities was frequent. There was a tendency for the opacities to appear suddenly before, coincident with, or after the onset of arthritis. Reference was also made to the fact that only a few round opacities may be present, and in many instances the lesions become confluent and may be indistinguishable radio- graphically from progressive massive fibrosis. It was suggested that more cases would be recognized if it were realized that there is often a mixed radio- graphic picture of round opacities and opacities indistinguishable from progressive massive fibrosis and tuberculosis.