A solitary amyloid nodule in the lung.

Solitary primary amyloid nodule of the lung is rare. Only eight cases have been reported. Our patient was a 66-year-old retired furnaceman who had an asymptomatic, smooth, round shadow in the right lower lobe, discovered accidentally on routine chest radiography. Right lower lobectomy was performed and a firm round nodule was found in the lateral basal segment. Its cut surface had a yellow-grey tinge and stained mahogany brown with Lugol's iodine. Microscopically the nodule consisted of uniformly eosinophilic-staining material with scattered multi-nucleate giant cells and groups of lymphocytes, plasma cells, and mononuclear cells at the edge. As the material stained with Congo red and gave typical greenish birefringence under polarized light it was evidently amyloid.