Tracheobronchomegaly, also known as Mounier-Kühn's Syndrome, is characterized by market dilation of the trachea and main bronchi and has been reported in association with several conditions, particularly connective tissue disease. The pathogenesis and clinical signs of light chain deposition disease are similar to those of light chain amyloidosis, in which these chains are deposited as amorphous material lacking the tinctorial features of the amyloid. We present a case involving both entities, an association that has not been previously reported, and we review the main characteristics of both diseases.