Ting Wei1, Sara Shalin2, Elizabeth Draper3, Emily Miller4, Haihong Zhang5, Ravi Sun5, Madison Lee5, Gregory Albert6, Gresham T Richter5,7. 1. Center for Investigation of Congenital Anomalies of Vascular Development, Department of Otolaryngology, University of Arkansas for Medical Sciences, Little Rock, AR, USA. twei@uams.edu. 2. Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, USA. 3. Hendrix College, Conway, AR, USA. 4. University of Arkansas for Medical Sciences, Little Rock, AR, USA. 5. Center for Investigation of Congenital Anomalies of Vascular Development, Department of Otolaryngology, University of Arkansas for Medical Sciences, Little Rock, AR, USA. 6. Department of Neurosurgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA. 7. Division of Pediatric Otolaryngology, Arkansas Children's Hospital, Little Rock, AR, USA.
Abstract
BACKGROUND: Vascular malformations are characterized by anomalous vascular channels with fragile walls and a propensity to bleed. Arteriovenous malformations (AVMs) in particular have disorganized vascular spaces with intervening fibrosis. Characterization of the structural abnormalities of these vessels has not been comprehensively evaluated. We hypothesize that AVMs are likely to demonstrate altered elastic and collagen fiber organization and distribution, reflecting their fragility, vascular instability, and abnormal development. METHODS: Fifteen AVMs were histologically evaluated by H&E, elastin and trichrome staining. To identify potential differences between extracranial and intracranial AVMs, 5 AVMs were harvested from the brain (n=5) and 10 from extracranial sites involving the skin and deep soft tissue (n=10). RESULTS: The elastin staining demonstrated reduplication, fragmentation and disruption of internal elastic lamina as well as irregular thickness, and inconsistent vascular density of all AVM specimens. Trichrome staining revealed thickening of the intimal layers of AVM arteries and demonstrated an irregular thickness of venous walls within the malformation and some areas of medial degeneration. Intracranial AVMs are characterized by more intramural inflammation with predominant neutrophil and lymphocyte infiltration. In contrast, extracranial AVMs display more extravascular inflammation with mast cell and neutrophil infiltration. Microvascular proliferations intervening between larger blood vessels were also noted in both types of AVMs, but more obvious in extracranial AVMs. CONCLUSION: These observed histologic anomalies of AVMs demonstrate disorganized deposition of elastin and collagen that point to the clinically observed vascular instability and fragility of these lesions.
BACKGROUND:Vascular malformations are characterized by anomalous vascular channels with fragile walls and a propensity to bleed. Arteriovenous malformations (AVMs) in particular have disorganized vascular spaces with intervening fibrosis. Characterization of the structural abnormalities of these vessels has not been comprehensively evaluated. We hypothesize that AVMs are likely to demonstrate altered elastic and collagen fiber organization and distribution, reflecting their fragility, vascular instability, and abnormal development. METHODS: Fifteen AVMs were histologically evaluated by H&E, elastin and trichrome staining. To identify potential differences between extracranial and intracranial AVMs, 5 AVMs were harvested from the brain (n=5) and 10 from extracranial sites involving the skin and deep soft tissue (n=10). RESULTS: The elastin staining demonstrated reduplication, fragmentation and disruption of internal elastic lamina as well as irregular thickness, and inconsistent vascular density of all AVM specimens. Trichrome staining revealed thickening of the intimal layers of AVM arteries and demonstrated an irregular thickness of venous walls within the malformation and some areas of medial degeneration. Intracranial AVMs are characterized by more intramural inflammation with predominant neutrophil and lymphocyte infiltration. In contrast, extracranial AVMs display more extravascular inflammation with mast cell and neutrophil infiltration. Microvascular proliferations intervening between larger blood vessels were also noted in both types of AVMs, but more obvious in extracranial AVMs. CONCLUSION: These observed histologic anomalies of AVMs demonstrate disorganized deposition of elastin and collagen that point to the clinically observed vascular instability and fragility of these lesions.
Authors: Vanessa F Schmidt; Max Masthoff; Veronika Vielsmeier; Caroline T Seebauer; Özlem Cangir; Lutz Meyer; Antje Mükke; Werner Lang; Axel Schmid; Peter B Sporns; Richard Brill; Walter A Wohlgemuth; Natascha Platz Batista da Silva; Max Seidensticker; Regina Schinner; Julia Küppers; Beate Häberle; Frank Haubner; Jens Ricke; Martin Zenker; Melanie A Kimm; Moritz Wildgruber Journal: Cardiovasc Intervent Radiol Date: 2022-10-19 Impact factor: 2.797