Congenital incomplete fusion of superior mesenteric artery mimicking dissection

Both spontaneous SMA dissection and anatomical variants of GIT vasculature are well known entities. We present a case initially diagnosed as an SMA dissection on CT, but upon detailed review of the imaging findings was considered to be incompletely fused ventral segmental arteries--a rare anatomic variant not well described before. This finding is clinically significant, as it can mimic a vascular dissection and such a wrong diagnosis will lead to unnecessary investigation and intervention.

A 62-year-old male patient presented with abdominal pain of uncertain etiology. The initial CT revealed an abnormal appearance of the superior mesenteric artery (SMA) which was diagnosed as SMA dissection. However, the appearance of this 'dissection' was unusual and there was a mismatch between the clinical presentation and radiological findings. The scan was reviewed and a 3D reconstruction of the abdominal aortal and visceral arteries was performed. The abnormal appearance of the SMA was deemed to be from a congenital anatomical variant. A review of the embryological origin of gut vasculature provides a likely explanation for this appearance.

Ours is an unusual case of a developmental variant that has not been well described hitherto. Attention to the ancillary radiological signs and understanding the embryological origin of the abdominal vasculature is important to distinguish such variants from pathology.