Caplan's syndrome

Caplan's syndrome is the association of rheumatoid lung nodules and pneumoconiosis. Originally described in coal miners with progressive massive fibrosis, it may also occur in asbestosis, silicosis and other pneumoconioses.

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. The nodules may pre-date the appearance of rheumatoid arthritis by several years, but it is possible that articular manifestations of rheumatoid arthritis may never develop.

Treatment is with steroids (after tuberculosis has been excluded).

Notes:

• in 1953, Caplan reported on a "peculiar" nodular pattern on chest radiographs of Welsh coal miners with rheumatoid arthritis that differed from the typical coal workers' pneumoconiosis
  • however, in 1950, the Belgian rheumatologist Emile Colinet described a similar case of rheumatoid arthritis and concomitant pulmonary opacities in a 30-year-old woman with silica exposure
• Caplan published a further case with respect to this "peculiar" nodular pattern on chest radiographs of Welsh coal miners with rheumatoid arthritis that differed from the typical coal workers' pneumoconiosis - this condition was initially called Colinet-Caplan syndrome but Colinet's name was later dropped from the eponym (1)

Reference:

• Steven Ronsmans, Paul D. Blanc. Colinet–Caplan Syndrome: History of an Outbreak of Autoimmune Disease in Scouring Powder Workers. Ann Intern Med. [Epub 10 January 2023]. doi:10.7326/M22-2630