Anatomical bases for the radiological delineation of lymph node areas. Part III: Pelvis and lower limbs.

Cancer spreads locally through direct infiltration into soft tissues, or at a distance by invading vascular structures, then migrating through the lymphatic or blood flow. Although cancer cells carried in the blood can end in virtually any corner of the body, lymphatic migration is usually stepwise, through successive nodal stops, which can temporarily delay further progression. In radiotherapy, irradiation of lymphatic paths relevant to the localization of the primary has been common practice for decades. Similarly, excision of cancer is often completed by lymphatic dissection. Both in radiotherapy and in surgery, advanced knowledge of the lymphatic pathways relevant to any tumor location is an important information for treatment preparation and execution. The third part of these series describes the lymphatics of the pelvis and the lower limb. It Provides anatomical bases for the radiological delineation of lymph nodes areas in the pelvic cavity and in the groin. It also offers the first original classification for labeling the intrapelvic nodes, grouped in seven paired volumes (called levels I-VII), functionally linked with one another and lower abdominal levels by eight potential drainage pathways.