A rare case of inferior mesenteric artery arising from the superior mesenteric artery, with a review of the review of the literature.

Anatomical variations of the inferior mesenteric artery (IMA) are uncommon. Generally, the IMA is very stable, arises directly from the abdominal aorta at the level of the third lumbar vertebra. We describe here an extremely rare case in which the IMA arose from the superior mesenteric artery. The findings were made during routine dissection of the cadaver of a 79-year-old Japanese man. This present case is the ninth report of this variation and was associated with gastrophrenic trunk, hepatosplenic trunk, hypoplastic spleen and accessory spleen. Clinically, cases like this highlight the importance of knowing the IMA anatomy and the possibility of its numerous variations in surgical procedures such as right hemicolectomy, resection of the transverse colon, left hemicolectomy, sigmoidectomy, and en bloc resection of the head of the pancreas and the superior mesenteric vessels. The developmental significance of this variation is also discussed with a detailed review of the literature.