From the Guidelines
The Riedel's lobe of the liver is a normal anatomical variant that requires no treatment, as it represents a variation rather than a pathological condition. This downward projection of liver tissue is typically found in the right lower quadrant of the abdomen and can sometimes be mistaken for an abdominal mass or enlarged organ during physical examination. The importance of recognizing this variant lies in avoiding unnecessary diagnostic procedures or interventions when it is incidentally discovered during physical examination or imaging studies. Some key points to consider when evaluating the Riedel's lobe of the liver include:
- It is generally asymptomatic and occurs more commonly in women than men
- It may be more noticeable in individuals with a thin body habitus
- Ultrasound or CT imaging can confirm the diagnosis by demonstrating the continuous nature of the tissue with the rest of the liver, as seen in the management of liver cancer 1. In the context of liver cancer management, surgical liver resection or percutaneous liver ablation is usually appropriate for peripheral intrahepatic lobar cholangiocarcinoma that is <3 cm with no biliary ductal dilatation, macroscopic vascular invasion, regional lymphadenopathy, or distant metastases 1. However, this is not directly relevant to the Riedel's lobe, which is a benign anatomical variation. Physicians should be aware of this normal variant to prevent misdiagnosis of hepatomegaly or abdominal tumors.
From the Research
Definition and Prevalence of Riedel's Lobe
- Riedel's lobe of the liver is a rare anatomical variant, often incidentally found on imaging or through the presence of hepatomegaly on physical examination 2.
- It is characterized by a downward tongue-like projection of the anterior edge of the right lobe of the liver to the right of the gallbladder 3.
- The prevalence of Riedel's lobe is dependent on age-related changes in liver size and skeletal shape, with an increased prevalence in the 50-59 age group 4.
Clinical Presentation and Complications
- Patients with Riedel's lobe are usually asymptomatic, but the presentation can vary, ranging from nonspecific symptoms to more severe issues such as torsion, obstruction, rupture, and bleeding 2.
- Riedel's lobe can be complicated by its torsion or hepatic tumors, and it is essential to consider this condition in patients undergoing cross-sectional imaging 3.
- There have been cases where Riedel's lobe was found incidentally, with invasive adenocarcinoma arising from close proximity, highlighting the importance of surveillance in this patient population 5.
Diagnosis and Imaging
- Riedel's lobe can be detected incidentally with abdominal imaging performed for other indications, such as CT scans or liver scintigraphy 5, 6.
- Liver scintigraphy can detect the presence of a hypertrophied Riedel's lobe and is recommended in all cases of right-sided abdominal masses 6.
- Cross-sectional imaging, such as CT scans, can help identify the presence of Riedel's lobe and any potential complications, such as torsion or hepatic tumors 3, 4.