From the Research
Internal iliac lymph nodes are distinguished from external iliac lymph nodes on a CT scan by their anatomical relationship to the iliac vessels, with internal nodes following the internal iliac artery and external nodes following the external iliac artery. To differentiate them, focus on their location along the iliac vessels - internal nodes are located deep in the pelvis, medial to the pelvic sidewall, while external nodes are found more anterolaterally in the pelvis near the inguinal ligament 1. Internal iliac nodes drain pelvic organs including the bladder, rectum, prostate, and cervix, while external iliac nodes receive drainage from the lower extremities and lower abdominal wall.
- Key characteristics of internal iliac lymph nodes include:
- Location along the internal iliac vessels
- Drainage of pelvic organs
- Typically smaller in size compared to external iliac nodes
- Key characteristics of external iliac lymph nodes include:
- Location along the external iliac vessels
- Drainage of lower extremities and lower abdominal wall
- Typically larger in size compared to internal iliac nodes Normal lymph nodes on CT should measure less than 10mm in short axis, with enlargement potentially indicating infection, inflammation, or malignancy 2. Radiologists typically report the specific location, size, and characteristics of these nodes, which helps clinicians determine their clinical significance in relation to potential pathology in the corresponding drainage areas.
- The most recent and highest quality study 1 suggests that PET/CT can predict the presence of metastatic lateral pelvic lymph nodes with a high degree of accuracy, which can aid in the differentiation and management of internal and external iliac lymph nodes.
- It is essential to consider the anatomical relationship and drainage patterns of internal and external iliac lymph nodes to accurately distinguish between them on a CT scan and provide appropriate clinical management.