Primary pulmonary amyloidosis misdiagnosed as malignancy on dual-time-point fluoro-deoxyglucose positron emission tomography/computed tomography: A case report and review of the literature.

Primary pulmonary amyloidosis is an uncommon manifestation, characterized by amyloid deposition in the lungs and other associated tissue. The clinical presentation of amyloidosis is variable, with non-specific symptoms. The current study reports the case of a 59-year-old female presenting with primary pulmonary amyloidosis, indistinguishable from lung malignancy based on 18F-fluoro-deoxyglucose (18F-FDG) accumulation on dual-time-point (DTP) FDG-positron emission tomography/computed tomography (PET/CT) imaging and the similarities in morphological changes. A percutaneous CT-guided thoracoscopic biopsy was subsequently performed. Histological examination revealed that the specimens contained amorphous, homogeneous material with a number of polyclonal plasma cells, lymphocytes and giant cells. A diagnosis of primary nodular parenchymal pulmonary amyloidosis was determined, and the patient was discharged without chemotherapy. The patient remained in good clinical condition during follow-up. The present case indicated that localized nodular amyloidosis with increased FDG uptake on DTP FDG PET must be considered in the differential diagnosis of growing lung nodules, and that a histological examination must be conducted to distinguish this condition from malignancies of the lung.