Segmental mediolytic arteritis—electronmicroscopic and immunohistochemical study

Bilateral extensive cerebral infarction and mesenteric ischemia associated with segmental arterial mediolysis in two young women

“…Another factor that may be involved in the pathogenesis of SAM is autoimmunity. Previous reports demonstrated IgG in arterial gaps, intact portions of the media, degenerated internal elastic lamina (IEL) and in the external elastica lamina (EEL), IgM in the intima layer, IEL and EEL and IgM and C3a in the lytic media neovessels 7,13 . Moreover, SAM has been described in association with autoimmune diseases, such as systemic lupus erythematosus (SLE), Crohn's colitis 8,11 and Graves disease in one of the present patients.…”

“…Moreover, SAM has been described in association with autoimmune diseases, such as systemic lupus erythematosus (SLE), Crohn's colitis 8,11 and Graves disease in one of the present patients. We cannot rule out that the idea that these associations are coincidental, but the rarity of this arteriopathy and the relatively low prevalence of SLE and Crohn's disease in conjunction with the presence of antibodies and complement in affected vessel walls from some patients 7,13 favor this hypothesis. The search for IgG and IgM deposits in the arterial wall of patient 2 was negative, but this result could be not totally representative, because the frozen sample could not fully represent the histological features of SAM (this pathology affects vessels in a discontinuous pattern).…”

“…The mediolysis can bring complications such as arterial rupture, formation of aneurysms and arterial dissection 2 . Healed lesions can exhibit foci of collagenization and neovessels in the media, thinning, fragmentation, reduplication and distortion of internal elastic lamina and thickening of the subendothelial layer and intima 2,9 , 13 . Focal medial and subintimal Alcian‐Blue‐positive deposits of unknown origin have also been described 9–11 …”

“…Some of the histological features of SAM, particularly of the healed lesions, are similar to those found in fibromuscular dysplasia (FMD), suggesting that SAM can be a precursor of some types of FMD 14 . However, the etiology of SAM is uncertain, with the main hypothesis being vasospasm 2,3 , 13 . It has been proposed that an inappropriate vasoconstrictive response of arteries to vasomotor stimuli could cause vasospasm and result in vascular injury 2 .…”

Systemic lupus erythematosus with hepatic aneurysm, Valsalva sinus aneurysm and associated polyangiitis: aneurysmal wall remodeling with dense fibrosis and calcification mediated by residual smooth muscle cells

“…4,11,18 The extracellular matrix of this aneurysmal wall had also remodeled as suggested by the mediating mechanism of these residual smooth muscle cells. Massive dystrophic calci cation and degeneration or remodeling of the extracellular matrices might be mediated by residual atrophic smooth muscle cells observed in this study, as suggested 4 by Juovonen et al 19 and Bode et al 16 In this aneurysmal wall, neither positive immunostaining for CMV nor viral particles in the ultrastructural study could be detected. 4 The residual atrophic smooth muscle cells were different from the literal descriptive features of myo broblasts (a broblastic spindle-shaped cell with well developed RER and rich intracytoplasmic laments with peripheral dense patches with similar immunohistochemical features).…”