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 vagina 1
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. (2004) Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 45 (9): 1509-18. Pubmed
- 3. Heesakkers RA, Hövels AM, Jager GJ, van den Bosch HC, Witjes JA, Raat HP, Severens JL, Adang EM, van der Kaa CH, Fütterer JJ, Barentsz J. 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. (2008) The Lancet. Oncology. 9 (9): 850-6. doi:10.1016/S1470-2045(08)70203-1 - Pubmed
- 4. Yun Mao, Sandeep Hedgire, Duangkamon Prapruttam, Mukesh Harisinghani. Imaging of Pelvic Lymph Nodes. Current Radiology Reports. 2 (11): 70. doi:10.1007/s40134-014-0070-z