Nodular AL Amyloidosis — An Unusual Etiology of a Solitary Pulmonary Nodule

Solitary pulmonary nodules (SPN) are defined as single intraparenchymal opacities less than 3 centimeters. The differential diagnosis of the SPN is broad. AL amyloidosis is a protein conformational disease which occurs when certain monoclonal light chains develop an unstable tertiary structure with resultant polymerization of insoluble amyloid fibrils that deposit in the extracellular space of sundry tissues. In the lung, diffuse interstitial amyloid deposition is the most common form of the disease