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Soft Tissue Tumors Part 3 - Muscle, Vascular, Nerve, Other
Vascular Tumors - Normal vessels
Author: Nat Pernick, M.D, PathologyOutlines.com, Inc.
Revised: 24 October 2009, last major update - October 2009
Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.
Definition
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● Normal vessels contain endothelial cells facing lumen and pericytes, smooth muscle cells and glomus cells towards outside of vessel
Normal histology
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● Vascular layers are outer tunica adventitia, intermediate tunica media and inner tunica intima; thickness depends on size and type of vessel
● Tunica adventitia: longitudinally arranged collagen; layer is larger in veins than arteries
● Tunica media: concentrically arranged smooth muscle whose diameter is altered by autonomic control; smooth muscle may secrete collagen, elastic fibers, elastic lamellae and proteoglycans; larger diameter in arteries than veins of similar size
● Tunica intima: inner endothelium and variable outer subendothelial connective tissue
● Capillaries: no muscular layer or elastic lamella; endothelial layer is complete, with pericytes present but difficult to identify on H&E
● Glomus cells: (a) modified smooth muscle cell with indistinct borders, pale cytoplasm, uniform nuclei; surround arterial segment of glomeriform arteriovenous anastomosis, which is richly innervated by autonomic nervous system fibers; or (b) peripheral chemoreceptor in carotid body and aortic body that detects hypoxia (Novartis Found Symp 2006;272:54); large, epithelioid cells with abundant cytoplasm and membrane bound, electron dense granules; richly supplied with nerve endings, diagram
● Pericytes: relatively undifferentiated cell that regulates microvascular blood flow (Histol Histopathol 1991;6:269, Microvasc Res 2009;77:235)
● References: University of Ottawa, Southern Illinois University
Aging related changes
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● Normal vascular structure changes during life, with progressive arterial stiffness
● Capillaries: basement membrane thickens with aging
Micro images
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Small arteries Small artery and vein Capillaries
Three layers: blue arrow at intima, Arterial wall
black bracket for media,
green bracket for adventitia
Artery: H&E Elastin stain Trichrome stain Arteriole
Venous wall Pericyte and endothelial interactions
Positive stains – endothelial cells
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● Vascular endothelium: CD34, CD31, Factor VIII related antigen, vimentin, Ulex europaeus I lectin (binds to alpha-L-fructose compounds), endothelin, von Willebrand factor; also FLI-1 (nuclear stain, AJSP 2001;25:1061)
● Lymphatic endothelium: similar staining as vascular endothelial cells but also D2-40+, LYVE1+, and only weakly Factor VIII related antigen+
● Pericytes: alpha smooth muscle actin, myosin, vimentin; also CD31
● Smooth muscle cells: actin, desmin
Electron microscopy
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● Endothelial cells: cells are jointed by tight, adherans or gap junctions; numerous pinocytotic vesicles, cytoplasmic microfilaments, microvilli, continuous basal lamina and Weibel-Palade bodies (membrane bound organelle which contains von Willebrand factor)
● Capillary endothelium: surrounded by basement membrane which contains pericytes, in contrast to lymphatic endothelium which contains little basement membrane
Electron microscopy images
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Brain capillary with endothelial Weibel-Palade bodies Endothelial junctions
cells and pericyte
Endothelial tight junction Pericytes
End of Soft Tissue Tumors Part 3 - Muscle, Vascular, Nerve, Other > Vascular tumors > Normal vessels
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