[Primary pulmonary amyloidosis with multiple nodules]

A 42-year-old man complained of a productive cough and exertional dyspnea. Roentgenogram and computed tomography of the chest showed several nodular shadows, and an open lung biopsy was done. Congo-red staining and electron microscopy showed the pulmonary nodules to be amyloid with infiltration by plasma cells and foreign body giant cells. The amyloid was identified as AL-lambda and kappa type by immunohistochemical examination, and plasma cells and foreign body giant cells contained light chains. In situ hybridization studies showed intens signals of lambda mRNA and kappa mRNA in the plasma cells, but no signal in the foreign body giant cells. The foreign body giant cells appeared to have phogocytosed the light chains. Electron microscopic examination showed an "amyloid star" in the foreign body giant cells. Morphologically, this observation showed that the amyloid was produced by the foreign body giant cells.