Caplan syndrome
Summary
Caplan syndrome is the coexistence of rheumatoid arthritis and a pneumoconiosis (classically coal worker's pneumoconiosis, but also silicosis and asbestosis), producing multiple peripheral pulmonary nodules. Nodules can cavitate and resemble necrobiotic rheumatoid lung nodules.
Detail
Also called rheumatoid pneumoconiosis. Patients are typically coal miners (or silica/asbestos-exposed workers) with seropositive rheumatoid arthritis who develop well-defined round nodules (0.5–5 cm) in the upper lung zones. Histologically the nodules show central necrosis with palisading histiocytes and surrounding dust-laden macrophages, similar to rheumatoid nodules elsewhere. The syndrome reflects an exaggerated immune response to inhaled dust in the setting of RA. Boards triad: coal miner + RA + multiple pulmonary nodules. Distinguish from progressive massive fibrosis (large coalescent upper-lobe masses without the RA serology) and from tuberculosis.
Sources
- First Aid for USMLE Step 1 2024
- Robbins Basic Pathology 10th ed
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