Caplan's syndrome

Caplan's syndrome (or Caplan's disease) is a combination of rheumatoid arthritis and pneumoconiosis that manifests as intrapulmonary nodules, which appear homogenous and well-defined on chest X-ray.^[1]

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Classification

Signs and symptoms

There is cough and shortness of breath. In addition there are the features of RA with painful joints 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.

Pathophysiology

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.

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.

Epidemiology

Incidence is currently 1 in 100,000 people but is likely to fall as the coal mining industry declines.

History

Caplan's syndrome was originally described in coal miners with progressive massive fibrosis.

References

1. ^ Ondrasík M (1989). "Caplan's syndrome". Baillieres Clin Rheumatol 3 (1): 205-10. PMID 2661027.