hepatic siderosis

Hepatic hemosiderosis, or hepatic iron overload, refers to the deposition of hemosiderin in the liver.

Pathology

Hepatic iron overload can be in the form of :

• diffuse
• heterogeneous
• segmental
• focal
• hypersiderosis
• intralesional siderosis
• periportal siderosis

In the absence of genetic hemochromatosis and systemic hemosiderosis, patients with cirrhosis can accumulate focal iron within regenerative or dysplastic hepatic nodules, commonly referred to as 'siderotic nodules'. Siderotic dysplastic nodules are considered premalignant lesions while siderotic regenerative nodules are a marker for severe viral or alcoholic cirrhosis.

Microscopic appearance

Siderotic nodules stain strongly with Prussian blue on histological specimens

Radiographic features

CT

If there are iron deposits above a certain level, siderotic regenerating nodules may appear as high attenuating nodules on CT or as heterogeneous regions of high-density liver parenchyma .

MRI

MRI is more sensitive than CT in demonstrating siderotic regenerating nodules. The detection of siderotic nodules can be improved with the use of GRE pulse sequences with longer TEs .

Regenerative siderotic nodules cannot be reliably distinguished from dysplastic siderotic nodules with MR imaging .

Reported signal characteristics of hepatic siderotic nodules and diffuse iron overload :

• T1: low signal
• T2: low signal
• gradient echo (GRE) with T2* weighting: low signal
• GRE T1-weighted in-phase and out-of-phase sequences: decreased signal on in-phase images compared to out-of-phase images (due to increased T2* effect on the in-phase images, which usually have longer echo times)

MR liver iron quantification is discussed separately.

See also

• hemosiderosis

Siehe auch:

• Hämochromatose

und weiter:

• Hämosiderose