Segmental Arterial Mediolysis (SAM) is an uncommon arteriopathy that results in lysis of smooth muscle portion of the arterial wall. This is not inflammatory or due to atherosclerosis. It is most often seen in the medium vessels in the abdomen including celiac, SMA and renal arteries. The above picture shows stenosis and dissection of the right renal artery due to SAM. It is a disease seen in middle age to older patients who present with abdominal pain due to underlying arterial aneurysms, dissections, occlusion from thrombosis or stenosis. If you would like to read more about SAM, look at this case report from cardiovascular interventional radiology 2014.