Caplan's syndrome

Synonyms and Associated Terms: Rheumatoid pneumoconiosis or Caplan's disease

Overview
Caplan syndrome is inflammation and scarring of the lungs in people with rheumatoid arthritis who have been exposed to coal dust. This combination of rheumatoid arthritis and pneumoconiosis manifests itself as intrapulmonary nodules, which appear homogenous and well-defined on chest X-ray.

Epidemiology and Demographics
Caplan's syndrome was originally described in coal miners with progressive massive fibrosis. Breathing in coal dust causes inflammation and scarring of the lung. Persons with rheumatoid arthritis are more likely to develop larger areas of inflammation and scarring in response to coal dust. Caplan syndrome is very rare in the United States. Incidence is currently 1 in 100,000 people but is likely to fall as the coal mining industry declines.

Signs and symptoms
There is cough and shortness of breath. In addition there are the features of RA with joint pain and morning stiffness. Examination should reveal tender, swollen MCP joints and rheumatoid nodules; auscultation of the chest may reveal diffuse râles that do not disappear on coughing or taking a deep breath.

Causes
The condition occurs in miners (especially those working in anthracite coal-mines), asbestosis, silicosis and other pneumoconioses. There is probably also a genetic predisposition and smoking is thought to be an aggravating factor.

Diagnosis

 * Chest radiology shows multiple, round, well defined nodules, usually 0.5-2.0 cm in diameter, which may cavitate and resemble tuberculosis.
 * Lung function tests may reveal a mixed restrictive and obstructive ventilatory defect with a loss of lung volume. There may also be irreversible airflow limitation and a reduced gas transfer factor.
 * Rheumatoid factor, antinuclear antibodies, and non-organ specific antibodies may be present in the serum.
 * Silicosis and asbestosis must be considered in the differential with TB.

Persons with Caplan syndrome may be at increased risk for tuberculosis (TB), and should be screened for exposure to TB.

Management
Once tuberculosis has been excluded, treatment is with steroids. All exposure to coal dust must be stopped, and smoking cessation should be attempted. Rheumatoid arthritis should be treated normally with early use of DMARDs.

Prognosis
The nodules may pre-date the appearance of rheumatoid arthritis by several years. Otherwise prognosis is as for RA; lung disease may remit spontaneously, but pulmonary fibrosis may also progress. Coal worker's pneumoconiosis uncommonly causes significant breathing difficulty or disability.

Acknowledgements
The content on this page was first contributed by: C. Michael Gibson, M.S., M.D.

List of contributors:David A. Kaufman, M.D., Assistant Professor, Division of Pulmonary, Critical Care & Sleep Medicine, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network.