Segmental Arterial Mediolysis: A Non-inflammatory, Non-atherosclerotic Arteriopathy Presenting as Abdominal Pain

Abstract

Segmental Arterial Mediolysis (SAM) is a rare non-inflammatory, non-atherosclerotic disease which involves medium sized vessels. It causes lysis and vacuolization of the arterial media, leading to thrombosis, aneurysm formation, or vessel rupture.Presentation varies from local pain to fatal bleeding.Figure 1In this case, a 49-year-old African American male presented with post-prandial right upper quadrant abdominal pain for few weeks.Physical examination and laboratory findings were unremarkable.Hepatobiliary ultrasound was negative.Due to the post-prandial nature of pain, CT- angiogram was obtained which showed soft tissue attenuation of the celiac trunk and main branches, and dissection within the celiac artery, consistent with SAM.Vasculitis work up was negative.He was managed conservatively with planned close out-patient follow up Differentiating SAM from vasculitis is important as immunosuppressive therapy is not recommended in SAM and can in fact be detrimental.Even though the etiology is not well understood, it is hypothesized to be related to repeated episodes of vasospasm.SAM is pathologically separated into two phases, an initial injurious phase and a reparative phase. The former is associated with vacuolization, smooth muscle loss, intramural hematoma and thrombosis.In the latter, there is fibrosis, stenosis, and smooth muscle restoration along with possible aneurysm formation or dissection with potential vessel rupture.The disease can run a self-limited course, hence the room for initial conservative approach, or can be associated with catastrophic complications.Although histology is the most definitive way for diagnosis, characteristic radiologic findings with negative serology are usually adequate in clinical practice.Endovascular intervention is a minimally invasive and reliable treatment option. In conclusion, although a definitive therapy has not been established, SAM occurs mostly with acute intra-abdominal hemorrhage and can be critical in some cases, making early diagnosis extremely important.