Internal Iliac Nodes

The internal iliac lymph nodes are a group of deep pelvic lymph nodes that lie along the branches of the internal iliac artery. They play a central role in the drainage of pelvic viscera, including reproductive organs, the bladder, rectum, and deeper portions of the perineum. These nodes are critical for immune defense and are frequently involved in the staging and spread of pelvic malignancies.

Structure

Internal iliac nodes are small, rounded, encapsulated lymphatic organs composed of lymphoid follicles, sinuses, and medullary cords. They are typically subdivided based on their position along the arterial branches of the internal iliac artery.

Subgroups (by artery association)

• Anterior division nodes: Along branches such as the obturator, uterine, vesical, and pudendal arteries
• Posterior division nodes: Along arteries like the superior gluteal and iliolumbar arteries
• Perirectal nodes: May be grouped with internal iliac nodes due to rectal drainage paths

Location

Internal iliac lymph nodes are found medial and posterior to the external iliac nodes, embedded in the pelvic connective tissue around the internal iliac artery and its branches. They are positioned along the pelvic sidewalls, near organs such as the bladder, rectum, and reproductive structures.

Function

• Lymphatic drainage: Receives lymph from:
  • Pelvic viscera: cervix, prostate, rectum, bladder, vagina, vas deferens, seminal vesicles
  • Deeper perineum and gluteal region
  • Communicates with sacral and external iliac nodes
• Immune response: Site of lymphocyte activation and antigen presentation
• Pathway to common iliac nodes: Efferent lymph drains into common iliac lymph nodes

Clinical Significance

• Cancer staging: Internal iliac nodes are key sentinel nodes in rectal, cervical, bladder, and prostate cancers
• Lymphadenopathy: May indicate local tumor spread or infection
• Pelvic surgeries: Often removed in pelvic lymph node dissections for oncologic control