Caplan's syndrome.

Caplan's syndrome is characterized by the presence of seropositive rheumatoid arthritis associated with a specific form of pneumoconiosis, consisting of multiple, well-defined homogeneous rounded opacities on chest X-ray. It develops especially in miners working in anthracite coal-mines and in persons exposed to silica and asbestos. In the development of the disease, genetic factors are considered to play an important role by influencing immunological reactivity of the organism exposed to various heteroantigens.