The external iliac lymph nodes can be found surrounding the external iliac artery and act as the draining nodes for several regions of the pelvis and lower limb.
The external iliac lymph nodes lie anterior to the internal iliac lymph nodes and usually form three separate subgroups according to their relation to the external iliac artery:
- considered the main channel of drainage
The efferent channels pass on towards the common iliac nodes. The nodes collect lymph from the:
- infraumbilical abdominal wall
- adductor region of the thigh
- glans penis/clitoris
- membranous urethra
- fundus of bladder
- uterine cervix and upper vagina1
Structural features remain as diagnostic standards for evaluation of pelvic lymph nodes. The size threshold of pelvic nodes ranges from 0.5 to 2 cm. A short axis diameter <1 cm in oval nodes or <0.8 cm in round nodes is considered the upper limit of normal.2 Using these parameters, the specificity for detecting positive pelvic nodes on CT reaches 97%, but with a low sensitivity of 34%.3
The external iliac nodes are an important nodal group when considering lymphatic spread of pelvic malignancy. The lymphatic drainage patterns of urogenital malignancies are complex in the pelvis; however, spread from the pelvic organs to the medial chain of the external iliac nodal group is the most common route through which metastasis can occur.4
- 1. Susan Standring. Gray's Anatomy. (2015) ISBN: 9780702052309
- 2. Torabi M, Aquino SL, Harisinghani MG. Current concepts in lymph node imaging. J Nucl Med. 2004;45:1509–18.
- 3. Heesakkers RA, Hovels AM, Jager GJ, van den Bosch HC, Witjes JA, Raat HP, et al. MRI with a lymph-node-specific contrast agent as an alternative to CT scan and lymph-node dissection in patients with prostate cancer: a prospective multicohort study. Lancet Oncol. 2008;9:850–6.
- 4. Mao Y, Hedgire S, Prapruttam D, Harisinghani M. Imaging of Pelvic Lymph Nodes. Current Radiology Reports. 2014;2(11):70.