Marfan’s and Loeys-Dietz syndromes predominantly affect the aorta, which made these etiologies less likely in our patient. Although FMD preferentially affects the renal artery and can involve the iliacs, the typical “string of beads” appearance of the affected vessels, which is seen in approximately 90% of patients with FMD,2 was not seen on angiography, making this diagnosis less likely. In addition, FMD affects women in approximately 90% of cases, further arguing against this etiology.2 Our patient had no risk factors or imaging findings consistent with atherosclerotic disease. Therefore, we felt the most likely diagnoses were EDS IV or SAM.
EDS IV (vascular type) is a rare disorder that portends a significant risk of morbidity and mortality stemming from arterial or visceral rupture.3 Although EDS IV is inherited in an autosomal dominant pattern, studies suggest that approximately 50% of patients have de-novo mutations. In contrast to other types of EDS, large joint hypermobility is absent, although hyperextensibility of small joints can be observed in some patients. Other manifestations may include intestinal or uterine rupture, pneumothorax, translucent skin, characteristic facial appearance, acrogeria (aged appearance of the hands), tendon or muscle rupture, early onset of varicose veins and gingival recession.4 Eighty percent of patients are affected by the age of 40.3 Any large vessel can be affected in EDS IV, although the distal vessels of the extremities tend to be spared. The aorta, iliacs, renal, carotid and splanchnic vessels are most commonly affected.3 The diagnosis can be confirmed by testing for abnormalities in the COL3A1 gene, although some patients with EDS IV will not have detectable gene mutations.4
Our patient had a pattern of vascular involvement compatible with EDS IV, as well as easily visible veins, perhaps suggesting skin translucency. Therefore, we pursued testing for abnormalities in the COL3A1 gene.
SAM is a rare noninflammatory vasculopathy, which leads to vacuolization of tissue in the outer portion of the media and separation of the media from the adventitia (“mediolysis”), ultimately leading to aneurysm and/or dissection. SAM can affect individuals of any age, but generally affects patients in the fifth to sixth decade of life, with a slight male predominance.5 The renal arteries (sometimes leading to renal infarcts), celiac and superior mesenteric arteries and their branches are most commonly affected; however, iliac artery involvement has also been reported.5 Because of the arteries involved, histologic confirmation of the diagnosis can be challenging, and frequently, the diagnosis relies on imaging findings of dissection and/or aneurysm in the appropriate vascular distribution and exclusion of other etiologies discussed previously. Notably, in light of our patient’s presentation, several authors have reported that SAM can evolve rapidly, involving multiple vascular beds in a matter of weeks.6
