Purpose: Segmental arterial mediolysis (SAM) is a rare vasculopathy of unknown etiology. It is non-atherosclerotic, non-inflammatory, non-hereditary, non-infectious, large to medium-sized arteriopathy. SAM is a condition which in some circumstances behaves as a vasculitis mimicker and should be recognized in order to provide appropriate treatment and avoid unnecessary immune-supressive therapy. SAM may be asymptomatic, or may present acutely as abdominal or flank pain, gastrointestinal bleeding, back pain, chest pain, hypotension, hematuria or stroke, depending on the vessel involved. Other presenting manifestations include prolonged abdominal pain, hypertension, hematuria or possible no symptoms. Typical arterial imaging features are sometimes difficult to distinguish from those of vasculitis, and include presence of dissection, fusiform aneurysms, occlusion, beaded appearance, or wall thickening.
Materials and Methods: We report a single center experience of 6 consecutive SAM cases (3 males and 3 females). A literature search of cases reported with SAM was performed and data summarized.
Results: Abdominal or flank pain was the presenting symptom in 5 of the 6 patients (table 1). CT angiography (CTA) was the method of diagnosis in all 6 patients. 3 patients (4,5,6) underwent therapeutic angiography; 2 with angiographic embolization because of bleeding, and one patient needed a stent insertion because of left renal infarction. 2 patients (4,6) underwent FDG-PET to rule out vasculitis. Serological tests were negative in all case, but C-reactive protein was elevated in 4 of them. 2 patients were treated with angiographic embolization due to bleeding, 2 treated with anti-platelet therapy, one with stent insertion, and one with antihypertensive treatment.
A medical literature review of 160 additional cases (table 2) shows that abdominal or flank pain was the chief complaint in the vast majority of the cases. Renal and abdominal medium-sized arteries were the most commonly involved. CTA was the preferred method of diagnosis.
Conclusion: SAM should be suspected in cases presenting with abdominal or flank pain. Angiographic features should be carefully studied by experienced radiologists to rule out vasculitis.
