Electron-microscopic examination of primary diffuse tracheobronchial amyloidosis. Role of fibroblasts in amyloid formation.

The author reports on the electron-microscopic examination of the diffuse tracheobronchial amyloidosis of a 51-year-old patient. The amyloid deposits were located in the lamina propria of the tracheal and bronchial mucosa. At the edge of the nodular deposits, condensation and radial arrangement of amyloid fibrils could be seen. Closely connected with the amyloid, active fibroblasts were present and their cytoplasm contained amyloid fibrils. The cell membrane of the fibroblasts was missing in part. Intracellular amyloid fibrils mingled with extracellular deposits. It can be assumed that active fibroblasts play an important role in local amyloid formation.