Caplans syndrome overview
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Caplan syndrome is known as rheumatoid pneumoconiosis. This is a combination of Rheumatoid Arthritis and pneumoconiosis. It is a rare syndrome occurring mostly in miners exposed to silica, coal and asbestos. For the first time, Caplan, a British physician in 1953 first described this syndrome. It is hypothesized that silica get ingested by macrophages. Silica destroys the macrophages and again engulfed by another macrophage. This repeating process leads to chronic inflammation and fibrosis. Due to having the capability to move around, silica can travel to other organs away from lung and can induce autoantigens. Silica has an adjuvant effect on antibody production. In patients with silicosis , increased rheumatoid factor and antinuclear antibodies has been found. By producing TNF α and Interleukin 1 , silica induces joint destruction. Silica also plays a role in inducing both innate and adaptive immunity. Patients with Caplan syndrome are mostly asymptomatic but in advanced stages dyspnea and cough might occur. In Caplan syndrome, increased inflammatory markers are found in serum study though there is no arthritis. Caplan syndrome with polyarthritis mostly positive for Anti citrullinated Peptide Antibodies (ACPA). Caplan nodules can appear with or before the onset of arthritis. In many cases miners have typical radiographic pictures of Caplan syndrome without any features of Rheumatoid Arthritis. Chest X ray findings of Caplan syndrome is characterized by well defined lung nodules of 0.5-5 cm throughout the lungs but predominantly in the peripheral areas. These nodules might appear as crops and later coalesce into a larger one. The onset of nodules are sudden, rapidly growing and can remain in the lungs for years longer. They might regress spontaneously unless get cavitated or calcified. Pleural effusion and pneumothorax are rare complications. CT scan findings are similar to chest x ray but provides more specific information such as mixed nodular infiltrative changes in lungs. Biopsy is required to confirm the diagnosis. [1] [2]