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Published on: August 9, 2019
Inguinal lymph nodes: size, number, and other characteristics in asymptomatic patients by CT
Nicholas Bontumasi1, Jon A Jacobson, Elaine Caoili
1Department of Radiology, University of Michigan Medical Center, 1500 East Medical Center Drive, TC-2910L, Ann Arbor, MI, 48109-0326, USA.
Insights
Normal inguinal lymph nodes in asymptomatic patients measure a mean short axis of 5.4 mm, with 8.8 mm at two standard deviations above the mean. These nodes are typically multiple, symmetric, oval, and contain fat.
Area of Science:
- Radiology
- Medical Imaging
- Anatomy
Background:
- Establishing normative data for anatomical structures is crucial for accurate diagnosis.
- Inguinal lymph node appearance on CT can be variable and requires defined parameters for interpretation.
Purpose of the Study:
- To establish normative data for the computed tomography (CT) appearance of inguinal lymph nodes in asymptomatic individuals.
- Provide reference values for size, number, and morphology of normal inguinal lymph nodes.
Main Methods:
- Retrospective review of 77 asymptomatic patients' pelvic CT examinations.
- Characterization of bilateral inguinal lymph nodes by size (short axis), number, and presence of fat attenuation.
- Inclusion criteria ensured no lower extremity/perineum pathology or history of malignancy.
Main Results:
- Mean short-axis inguinal lymph node size was 5.4 mm (range 2.1-13.6 mm).
- Two standard deviations above the mean short axis was 8.8 mm.
- Mean superficial and deep inguinal lymph node counts were 10.7 and 1.2 per patient, respectively.
- Internal fat attenuation observed in 85% (superficial) and 78% (deep) of nodes.
- Oval shape noted in 95% (superficial) and 78% (deep) of nodes.
Conclusions:
- Normal inguinal lymph nodes in asymptomatic patients average 5.4 mm short axis, with 8.8 mm at two standard deviations.
- Nodes are typically multiple (4-20 per patient), symmetric, oval, and contain fat.
- Fat attenuation may be absent in smaller lymph nodes.
Purpose:
The purpose of this study was to establish normative data for the CT appearance of inguinal lymph nodes.
Materials And Methods:
After Institutional Review Board approval, search of the radiology information system identified 500 consecutive CT examinations of the pelvis. Patients were included if no lower extremity or perineum pathology, or history of malignancy at the time of CT examination, and a clinical note documenting no tumor at least 2 years after the CT. The final study group was 77 patients. CT examinations were retrospectively reviewed and bilateral inguinal lymph nodes were characterized by size (short axis and largest size in general), number, and presence of fat attenuation.
Results:
The mean short-axis inguinal lymph node size was 5.4 mm (range 2.1-13.6 mm), measured at 8.8 mm two standard deviations above the mean. The mean number of superficial and deep inguinal lymph nodes was 10.7 (range 3-18) and 1.2 per patient (range 1-2), respectively. Superficial and deep inguinal nodes showed internal fat attenuation in 85 and 78% of nodes, and were oval in shape in 95 and 78%, respectively.
Conclusion:
Inguinal lymph nodes in asymptomatic patients have a mean short axis of 5.4 mm, a short axis of 8.8 mm at two standard deviations above the mean, and are multiple and symmetric in size and number (4-20 per patient). Normal inguinal lymph nodes were commonly oval in shape and contained fat, although such findings may be absent in smaller lymph nodes.
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