Multiple nodular pulmonary amyloidosis in a patient with rheumatoid arthritis

Secondary amyloidosis is caused by the deposition of overproduced amyloid A (AA) protein as a consequence of chronic inflammation in patients with rheumatoid arthritis (RA). AA is most commonly deposited in the kidney and gastrointestinal tract, while pulmonary amyloidosis is a rare manifestation. We herein report a case of multiple nodular pulmonary amyloidosis in a 57-year-old Japanese man with a 7-year history of untreated RA and exposure to smoke and asbestos. He presented with tender swollen joints, cough and a fever. Computed tomography (CT) showed multiple pulmonary nodules with left pleural thickening and effusion. Positron emission tomography/CT (PET/CT) showed a mild ¹⁸F-fluorodeoxyglucose uptake consistent with left pleural thickening but a poor uptake in the pulmonary nodules. We performed endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of the nodules, and AA was detected in the obtained specimen. A subsequent thoracoscopic pleural biopsy revealed no malignancy. Prednisolone and methotrexate were administered for RA and resulted in a dramatic improvement of arthritis and serological abnormalities. Three years later, follow-up chest CT showed that all of the pulmonary nodules had shrunk. EBUS-TBNA and PET/CT might be useful for the differential diagnosis of nodular pulmonary amyloidosis.