Abstract

Lower-Limb Lymphatic Drainage Pathways and Lymph Nodes: A CT Lymphangiography Cadaver Study

Akira Shinaoka, MD, PhD • Seijiro Koshimune, MD • Hiroo Suami, MD, PhD • Kiyoshi Yamada, MD, PhD •  Kanae Kumagishi, PhD • John Boyages, MD, PhD • Yoshihiro Kimata, MD, PhD • Aiji Ohtsuka, MD, PhD

Background: Most lymphatic imaging examinations of the lower limb require intradermal or subcutaneous injection of tracer material into the foot to demonstrate the lymphatic vessels; however, no standard protocol exists, and single or multiple injections are applied at different sites.

Purpose: To determine the three-dimensional relationships between each lymphatic group of the lower limb and corresponding regional lymph nodes.

Materials and Methods: A total of 130 lower limbs (55 from men and 75 from women) from 83 fresh human cadavers were studied. Lymphatic vessels were first visualized by using indocyanine green fluorescent lymphography with 19 injection sites in the foot, classified into four distinct lymphatic groups (anteromedial, anterolateral, posteromedial, and posterolateral); dilute oil-based contrast material was then injected. Next, specimens were scanned with CT and three-dimensional images were analyzed.

Results: The anteromedial and anterolateral lymphatic groups of the lower-leg lymphatic vessels were independent of each other and connected to different regional lymph nodes in the inguinal region. The posteromedial group and the anteromedial group in the lower leg drained to the same inguinal lymph nodes. Only the posterolateral group of lymphatic vessels in the lower leg drained to the popliteal lymph nodes. Leg lymphatic drainage pathways were independent of genital pathways.

Conclusion: Standard injection sites at the web spaces between the toes did not help visualize some lymph nodes of the lower leg. Additional injection sites in the medial, lateral, and posterior aspect of the foot would be better for evaluating the whole lymphatic pathways and regional lymph nodes and for improving understanding of leg lymphedema.

Main findings

• This study identified suitable tracer injection sites for comprehensive imaging of the lower limb to help evaluate leg lymphedema.
• There are four lymphatic pathways in the lower leg (anteromedial, anterolateral, posterolateral, and posteromedial) that drain mainly to three lymph nodes; two nodes were in the superficial inguinal region and one node was in the popliteal region.
• Three lymph nodes in two inguinal regions (inferior lateral 1 and inferior lateral 2) and one lymph node in the popliteal region (superficial popliteal) receive almost three-quarters (73%) of the lymphatic drainage of the lower leg.
  The posterolateral lymphatic vessels of the lower leg were the only group connecting to the popliteal lymph node.
• Conventional lymphangiography injection protocols that use only injections into toe web spaces demonstrated only the anteromedial pathway and did not depict other lymphatic pathways.