Primary Amyloidosis With Hepatosplenic Involvement

Clinical History

65-year old male patient presented with 15 kilogram weight loss during the last 4 months. Allogen kidney transplantation had been performed four years ago because of end stage renal insufficiency of unknown etiology.

Imaging Findings

65-year old male patient presented with 15 kilogram weight loss within the last 4 months. Allogen kidney transplantation had been performed four years previously due to end stage renal insufficiency of unknown etiology. After non-enhanced multidetector-row spiral CT scans (MDCT; Volume Zoom, Siemens, Germany; collimation 2.5 mm) a contrast-enhanced MDCT scan was performed by administering 120 mL iodixanol (Visipaque 270, Nycomed Amersham, Norway) via a 20-gauge needle placed in an antecubital vein. The flow rate of the contrast agent was 3 mL/second, using an automated injector (Ulrich AG, Ulm, Germany). Non-enhanced MDCT scans of the abdomen show not well defined areas of low attenuation in the right lobe of the liver (Fig. 1a). In addition, small rounded calcification in the upper pole of the spleen are visible (Fig. 1b). Following intravenous contrast material administration, the liver and the spleen parenchyma demonstrate a heterogeneous enhancement with irregular, patchy and geographic areas of decreased attenuation (Fig. 2a and b). These hypodense areas are partially located within the parenchyma and along vessel walls, including the periportal area. This results to the observation of a periportal, hypoattenuating collar in this case (Fig. 2 a). Both the spleen and the liver are normal in size. There is normal perfusion of the transplanted kidney in the right iliac region (Fig. 3a), both atrophic kidneys in the renal fossa are visible (Fig. 3b). In addition, small retroperitoneal lymph nodes are seen.

Discussion

Amyloidosis is a complex disease that results in an extracellular deposition of fibrils of insoluble fibrillar protein-mucopolysaccharide complexes (amyloid) throughout the body. The current classification of amyloidosis is based on the nature of the precursor plasma proteins that form the fibril deposits. The most common type is AL (amyloid light-chain) amyloidosis (primary amyloidosis) with a fibril composition of monoclonal immunoglobin light chains. The clinical features of amyloidosis depend on the organs involved. The initial symptoms are frequently fatigue and weight loss. The organs most commonly involved are the kidney and the heart. Renal amyloidosis usually manifests as proteinuria, often resulting in the nephrotic syndrome, but rarely causing progressive renal failure. Diagnosis of amyloidosis is established by tissue biopsy. Radiological features of liver and spleen involvement include often a non-specific organ enlargement due to amyloid deposition (Ref. 1). Since amyloid is known to have an affinity for calcium deposition, radiographically visible calcifications may be present (Ref. 2). The liver and spleen parenchyma exhibit focal or diffuse areas of low attenuation, visible on both non-enhanced and contrast-enhanced MDCT scans (so-called “amyloid pseudotumor appearance”). These low attenuating areas correspond to areas of amyloid deposition which usually show delayed enhancement after administration of contrast material. Intrahepatic amyloid deposition may occur within the parenchyma itself, along the hepatic sinusoids, within the spaces of Disse, and along arteries and veins. This may be the reason for the observation of the periportal hypoattenuating collar in this case.

Differential Diagnosis List

Final Diagnosis

AL (amyloid light-chain) amyloidosis (primary amyloidosis) with hepatosplenic involvement

URL:	https://www.eurorad.org/case/1105
DOI:	10.1594/EURORAD/CASE.1105
ISSN:	1563-4086