[Amyloidosis and the respiratory tract].

Amyloidosis is a disease of protein metabolism characterized by the deposition of amyloid substance in several organs. Several types of amyloid protein exist and one of the possible classifications is primary, secondary or hereditary amyloidosis, based on the type of protein involved and whether there is another condition that leads to amyloidosis. One can also classify amyloidosis as localized or systemic. The authors present four cases of amyloidosis limited to the respiratory tract and revise this entity, its forms of presentation (tracheobronchial, nodular--solitary or multiple, and diffuse septal-alveolar), methods of diagnosis and of searching the systemic entity. The most important differential diagnosis is with neoplastic diseases; therefore a definite diagnosis is important as lung amyloidosis usually is a benign and indolent condition.