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Updated: May 1, 2026
Intravital Microscopy of the Inguinal Lymph Node
Published on: April 4, 2011
Contouring inguinal and femoral nodes; how much margin is needed around the vessels?
Carolyn H Kim1, Adam C Olson2, Hayeon Kim1
1Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
Purpose:
To determine the optimal margin needed around the femoral vessels for appropriate inguinofemoral lymph node coverage and to propose guidelines defined by anatomic boundaries for clinical target volume delineation.
Methods And Materials:
Twenty-two patients with pelvic malignancies and involved inguinal lymph nodes treated with conformal radiation therapy were selected. Lymph nodes were considered positive if they were pathologically malignant by biopsy, had 1(8)F-fluorodeoxyglucose avidity on positron emission tomography or measured ≥1.5 cm on computed tomographic scan. We measured distance from the center of node(s) to the edge of the nearest femoral vessel.
Results:
There were 52 total positive inguinal nodes among 22 patients. Relative to the femoral vessels, the location of the nodes were 51.9% anteromedial, 21.2% anterior, 11.5% anterolateral, 9.6% medial, 1.9% posterior, and 3.9% lateral. To cover ≥90% disease, the margins needed around the nearest femoral vessel were anteromedial ≥35 mm, anterior ≥23 mm, anterolateral ≥25 mm, medial ≥22 mm, posterior ≥9 mm, and ≥32 mm lateral. The corresponding anatomic boundaries were the following: laterally, medial border of the iliopsoas; medially, lateral border of adductor longus or medial end of pectineus; posteriorly, iliopsoas muscle laterally and anterior aspect of the pectineus muscle; medially and anteriorly, the anterior edge of the sartorius muscle. Most of the macroscopic nodes were medial or anteromedial to the femoral vessels. No patient had involved posterior or lateral nodes alone without positive nodes in the anterior or anteromedial positions.
Conclusions:
Circumferential margins around femoral vessels required to adequately cover this nodal region were >2 cm in most directions. Contouring the inguinal lymph nodes as a compartment defined by the anatomic landmarks suggested above may be more reproducible. Physicians should exercise caution in extrapolating pelvic nodal contouring guidelines to inguinal lymph nodal contouring.
Insights
Optimal margins around femoral vessels are crucial for covering inguinal lymph nodes in cancer patients. This study defines precise anatomical boundaries for radiation therapy planning, improving treatment accuracy.
Area of Science:
- Radiation Oncology
- Medical Imaging
- Surgical Anatomy
Background:
- Inguinofemoral lymph node involvement is common in pelvic malignancies.
- Accurate delineation of the clinical target volume (CTV) is essential for effective radiation therapy.
- Existing guidelines for pelvic nodal contouring may not be directly applicable to the inguinal region.
Purpose of the Study:
- To determine the optimal margin around femoral vessels for comprehensive inguinofemoral lymph node coverage.
- To propose evidence-based guidelines for CTV delineation using anatomical landmarks.
Main Methods:
- Analysis of 22 patients with pelvic malignancies and positive inguinal lymph nodes treated with conformal radiation therapy.
- Identification of positive nodes via biopsy, PET scan, or CT scan measurements (≥1.5 cm).
- Measurement of the distance from positive nodes to the nearest femoral vessel.
Main Results:
- 52 positive inguinal nodes were identified across 22 patients, predominantly anteromedial and anterior to the femoral vessels.
- Required margins around femoral vessels for ≥90% disease coverage varied by location: anteromedial ≥35 mm, anterior ≥23 mm, anterolateral ≥25 mm, medial ≥22 mm, posterior ≥9 mm, and lateral ≥32 mm.
- Defined anatomical boundaries include the iliopsoas, adductor longus, pectineus, and sartorius muscles.
Conclusions:
- Circumferential margins exceeding 2 cm around femoral vessels are generally needed for adequate inguinal lymph node coverage.
- Contouring the inguinal lymph node compartment using defined anatomical landmarks may enhance reproducibility.
- Caution is advised when applying pelvic nodal contouring guidelines to the inguinal region.
