FDG PET/CT in a Case of Caplan Syndrome.

Caplan syndrome is a rare disease characterized by pulmonary nodules in patients with rheumatoid arthritis with a history of exposure to inhaled inorganic dust particles. We describe FDG PET/CT findings and evolution of CT findings in a case of Caplan syndrome. FDG PET/CT showed multiple consolidations with moderate activity in both upper lobes, numerous small nodules with mild activity in both lungs, and multiple FDG-avid lymph nodes in the mediastinum and bilateral hila and axillae. Follow-up CT showed confluence of the consolidations in both upper lobes and emergence of multiple peripherally located well-defined cavitating nodules.