A human case of hypoplastic external iliac artery and its collateral pathways.

During a student dissection course held at the Tokyo Women's Medical University, in a 91-year-old human female cadaver we encountered a very rare case of a hypoplastic right external iliac artery. It continued into the normal femoral artery by anastomoses formed with the enlarged obturator and deep circumflex iliac arteries. While the obturator artery originated from the anterior branch of the internal iliac artery, the deep circumflex iliac artery was supplied by the iliolumbar artery, which in turn formed a common stem to arise from the lateral sacral artery. Whether the hypoplastic external iliac artery arose developmentally or secondarily could not be discerned, but the case nevertheless provides important information regarding the arterial anlage between the pelvis and lower extremity. The case is also clinically significant in that it indicates a possible collateral pathway if the external iliac artery is occluded or ischaemia.