title: Segmental arterial mediolysis.
abstract: Segmental arterial mediolysis (SAM) is an uncommon, nonatherosclerotic, noninflammatory, large- to medium-sized arteriopathy first described in 1976. It is characterized histologically by vacuolization and lysis of the outer arterial media leading to dissecting aneurysms and vessel rupture presenting clinically with self-limiting abdominal pain or catastrophic hemorrhages in the abdomen. Patients of all ages are affected with a greater incidence at the fifth and sixth decades. There is a slight male predominance. Imaging findings overlap with inflammatory vasculitis, collagen vascular disease, and fibromuscular dysplasia. The presence of segmental dissections involving the celiac, mesenteric, and/or renal arteries is the key distinguishing features of SAM. Inflammatory markers, genetic tests for collagen vascular disorders, and hypercoagulable studies are negative. Anti-inflammatory agents and immunosuppressants are not effective. A mortality rate of 50 % has been attributed to the acute presentation with aneurysmal rupture necessitating urgent surgical or endovascular treatments; in the absence of the acute presentation, SAM is a self-limiting disease and is treated conservatively. There are no established guidelines on medical therapy, although optimal control of blood pressure is considered the main cornerstone of medical therapy. The long-term prognosis is not known.
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA, anil.pillai@utsouthwestern.edu.
authors.forename: Anil Kumar
authors.initials: AK
authors.lastname: Pillai
authors.forename: Shams I
authors.initials: SI
authors.lastname: Iqbal
authors.forename: Raymond W
authors.initials: RW
authors.lastname: Liu
authors.forename: Niranjan
authors.initials: N
authors.lastname: Rachamreddy
authors.forename: Sanjeeva P
authors.initials: SP
authors.lastname: Kalva
mesh_terms: D000005:Abdomen / Q000098:blood supply*; D015746:Abdominal Pain / Q000175:diagnosis; D000784:Aortic Dissection / Q000175:diagnosis / Q000473:pathology / Q000628:therapy; D017542:Aneurysm, Ruptured / Q000175:diagnosis / Q000473:pathology / Q000628:therapy; D001158:Arteries; D003937:Diagnosis, Differential; D003952:Diagnostic Imaging; D006801:Humans; D015641:Radiography, Interventional; D014652:Vascular Diseases / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy*