Riedel lobe

Last revised by Ammar Ashraf on 6 Dec 2023

Riedel lobe is a common anatomical variant of the liver to be aware of because it can simulate a mass. Its misidentification as a pathologic abdominal mass has led to surgery. Pathology can also occur within it (e.g. malignancy or even torsion) and cause atypical hepatic symptoms low in the pelvis 1,2.

Some feel that the term Riedel lobe should be abandoned as it is not an accessory lobe but rather a variant of appearance of the right lobe.

Riedel lobe has an incidence of ~17.5% (range 3.3-31%) and is more frequently found in females (M:F = 1:3) 2,3.

Riedel lobe is a tongue-like, inferior projection of the right lobe of the liver beyond the level of the most inferior costal cartilage on cross-sectional images 1. It is not considered a true accessory lobe of the liver but an anatomical variant of the right lobe of the liver 3.

It was originally reported in 1888 by the German surgeon, Bernhard Moritz Carl Ludwig Riedel (1849-1916) 4 in seven female patients who had palpable masses in the right hypochondrium that were subsequently confirmed to be Riedel lobes at surgery 2

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 3
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  • Case 4
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  • Case 5: with hepatic steatosis and liver cystic mass
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  • Case 6
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