Amyloidosis: Review and imaging findings

Amyloidosis is a collection of pathophysiologically related disease entities caused by the extracellular deposition of abnormal fibrillar proteins called amyloid. The accumulation of amyloid may be systemic, involving many organs, or localized manifesting as infiltration of individual organs, or in the form of a focal, tumorlike lesion. Amyloidosis may develop in the setting of underlying conditions, usually chronic inflammatory diseases, in which case it is termed secondary, or it may involve no underlying disease and thus be primary or idiopathic. Amyloid infiltration leads to pathology through the disruption of normal tissue structure and function or through cytotoxic effects of intermediate forms of protein aggregates. Clinical manifestations of the disease vary and are nonspecific, increasing the need of imaging during the investigation of the disease. Imaging findings are diverse and not pathognomonic; however, combined with the patient's clinical history they can raise the suspicion of amyloidosis and direct toward its confirmation by biopsy. Radiologists should be familiar with the appearance of amyloidosis in various modalities to aid the early identification of the disease and direct toward prompt treatment planning. Such knowledge would provide the radiologist with an opportunity to contribute to patient care and aid reducing the high morbidity and mortality of the disease.