Mimicking pulmonary multiple metastatic tumors: A case of primary nodular parenchymal pulmonary amyloidosis with review of the literature

Abstract

Abstract. Primary pulmonary amyloidosis is a relatively rare condition, characterized by amyloid deposition in the lungs and other associated structures. We report a case of primary nodular parenchymal pulmonary amyloidosis in a 44-year-old male. The patient was referred to our hospital for further evaluation of multiple lobulated nodules in both lungs. As the multiple lung nodules were suspected to be metastatic, 18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) was conducted, which revealed that the nodules had a mild uptake of 18 F-FCG. Amyloidosis was confirmed by conducting a percutaneous CT-guided fine-needle aspiration (FNA) biopsy in the left lung nodule. A literature review of previous studies on primary nodular parenchymal pulmonary amyloidosis from Medline (1970-October 2011 and Embase (1989-October 2011 was also included. Despite its rarity, primary nodular parenchymal pulmonary amyloidosis with a pattern of multiple nodules also forms part of the differential diagnosis of pulmonary metastases with high 18 F-FDG uptake on PET/CT.

18F-FDG PET/CT in Patients with Nodular Pulmonary Amyloidosis: Case Report and Literature Review

“…There were 16 male and 23 female cases, while the age and gender were not indicated in 2 cases [ 9 , 12 ]. Ages ranged from 32 to 85 years and, consistent with previous findings [ 17 , 18 , 24 ], the average age of the patients was in the sixth decade (64 years).…”

“…We identified 19 articles [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ] describing pulmonary amyloidosis and PET/CT scan in Medline, EmBase and the ISI Web of Science. Data on the clinical presentation, histopathological and imaging findings of 41 patients (including our case) are summarized in table 1 (PET positive) and table 2 (PET negative).…”

“…The most common presentations are nephrotic syndrome, idiopathic peripheral neuropathy, cardiomyopathy, and unexplained hepatomegaly [ 1 ]. Pulmonary involvement rarely causes symptoms unless gas exchange in alveolar structures is severely affected by amyloid deposits [ 2 , 18 , 24 ]. Histologically, amyloid deposits are identified on the basis of eosinophilic amorphous deposits which take up Congo red stain and typically exhibit apple-green birefringence when examined under polarized light [ 1 , 7 , 22 , 24 , 25 ].…”

“…The size of the nodules varies from a few millimeters to several centimeters. It is usually a silent disease and found incidentally on chest radiographs in asymptomatic, older individuals [ 17 , 18 , 19 , 24 , 25 ]. It may show a slow progression of increased size or number of nodules but not always reveals a restrictive pattern of lung function or impairment of gas exchange.…”

“…It may show a slow progression of increased size or number of nodules but not always reveals a restrictive pattern of lung function or impairment of gas exchange. The natural history of nodular pulmonary amyloidosis is associated with a relatively benign prognosis [ 2 , 18 , 19 , 21 , 25 ].…”