¹⁸F-fdg pet scanning in pulmonary amyloidosis

¹⁸F-FDG PET plays an important role in the evaluation of patients with lung malignancies but can lead to false-positive and falsenegative results. Very little is known about ¹⁸F-FDG PET scanning in amyloidosis. Methods: A computer-assisted search of medical records was conducted to identify subjects with pulmonary amyloidosis (confirmed by biopsy) who were seen at the Mayo Clinic during a 15-y period between January 1, 1997, and December 31, 2011, and had a PET scan available for current review. Results: Eighteen patients were diagnosed to have amyloidosis by lung biopsy (15 surgical, 2 transthoracic needle, and 1 bronchoscopic). The mean age of the patients was 64.8 y (range, 32-80 y). Seventeen patients had primary amyloidosis, including 5 with Sjögren syndrome, 1 with rheumatoid arthritis, and 1 with multiple myeloma. The most common abnormal findings on the chest CT scan were pulmonary nodules (n = 14), followed by cysts (n 5 6) and reticular opacities (n = 4). Eight patients had positive ¹⁸F-FDG PET results (intrathoracic ¹⁸F-FDG uptake), including 4 patients with coexisting mucosa-associated lymphoid tissue lymphoma (maximal standardized uptake value [SUV_max] range, 3.1-6.7) and 1 patient with a pleural plasmacytoma (SUV_max, 7.2); the remaining 3 patients had amyloid only (SUV_max range, 2.1-3.2). Ten patients with negative PET results included 3 additional patients with mucosa- associated lymphoid tissue lymphoma. Conclusion: Positive ¹⁸F-FDG PET results, especially with an SUV_max of more than 3, in patients with pulmonary amyloidosis should raise suspicion about associated lymphoma or plasmacytoma, but negative PET results do not exclude the presence of such neoplasms.