CT evaluation of amyloidosis: spectrum of disease.

Amyloidosis is a rare systemic disease caused by extracellular deposition of an insoluble protein. Although it is usually seen in a systemic form, 10%-20% of cases can be localized. Systemic amyloidosis is subclassified into an idiopathic primary form and a secondary or reactive form. Patients with primary amyloidosis have no underlying condition or disease. Men are affected more than women, and the mean age at presentation is 55-60 years. Some causes of secondary amyloidosis are multiple myeloma (10%-15%), rheumatoid arthritis (20%-25%), tuberculosis (50%), or familial Mediterranean fever (26%-40%). Radiographic studies of 90 patients with biopsy-proved primary or secondary amyloidosis were reviewed. Computed tomographic (CT) scans demonstrated a wide spectrum of disease in the cardiothoracic, gastrointestinal, genitourinary, and musculoskeletal systems. Amyloid deposition simulated both inflammatory and neoplastic conditions. Amorphous or irregular calcifications were occasionally identified within the amyloid deposit. Definitive diagnosis requires biopsy confirmation, as CT findings are nonspecific.