Urogenital Imaging

Amyloidosis

a collective term for a group of diseases that are characterized by the widespread extracellular deposition of insoluble amyloid protein. The process is usually systemic, but localized forms are recognized. Clinical manifestations are protean, and result from organ dysfunction secondary to amyloid protein accumulation. Amyloidosis may be primary (idiopathic) or secondary. Secondary causes include myeloma, solid malignancies, and chronic inflammatory conditions such as rheumatoid arthritis and tuberculosis. In primary nonfamilial, amyloidosis and amyloidosis secondary to myeloma, the deposited protein is derived from immunoglobulin light chains. In nonmyelomatous secondary amyloidosis, the protein is derived from amyloid A protein, an acute phase reaction protein. Renal cell cancer is the commonest solid organ malignancy associated with secondary amyloidosis. Approximately 3% of patients with renal cell carcinoma have autopsy evidence of systemic amyloidosis, and this can occur in the absence of metastases. CT findings in amyloidosis are extremely variable and diverse. The usual sites of involvement in primary amyloidosis are kidneys, heart, lungs, gastrointestinal tract and skin, while the usual sites in secondary amyloidosis are kidneys, liver, spleen and adrenal glands.

Patients often present with renal insufficiency. Renal failure or cardiac failure are common causes of death. CT findings include tracheobronchial wall thickening, (which may be nodular or diffuse), parenchymal lung nodules (which may be calcified) or infiltrates, concentric cardiac wall thickening, pericardial effusion, adenopathy, gastric wall thickening (with or without ulceration), small bowel wall thickening, small bowel dilatation, mild hepatosplenomegaly, enlarged or contracted kidneys, renal masses, mild adrenal enlargement, bladder wall thickening, retroperitoneal infiltration, osteolytic bone lesions, and spondyloarthropathy with joint destruction and subchondral cysts. Many of these findings may also be seen on plain radiographs, MRI or ultrasound. Echocardiocartography may be helpful in demonstrating ventricular wall thickening, which has a characteristic speckled appearance in amyloidosis. For specific description see amyloidosis adrenal, amyloidosis bladder, amyloidosis ovarian, amyloidosis prostatic, amyloidosis renal, amyloidosis seminal vesicles, amyloidosis ureteric, amyloidosis urethral.

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