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 .
Some feel that the term Riedel lobe should be abandoned as it is not an accessory lobe but just a variant of the 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) .
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 . It is not considered a true accessory lobe of the liver but an anatomical variant of the right lobe of the liver .
History and etymology
It was originally reported in 1888 by the German surgeon, Bernhard Moritz Carl Ludwig Riedel (1849-1916) in seven female patients who had palpable masses in the right hypochondrium, which were subsequently confirmed at surgery .