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Which of the following regarding normal vessels is INCORRECT?

A) Endothelial cells express CD31, CD34, von Willebrand factor, and Ulex europaeus lectin-1.

B) Pericytes and smooth muscle cells express smooth muscle actin and α-smooth muscle actin.

C) Lymphatic endothelial cells express LYVE-1 and podoplanin (D2-40).

D) Endothelial cells play an important role in antigen presentation and cytokine secretion.

E) Both large arteries and veins contain a prominent internal elastic lamina that can be highlighted with an elastic stain.

The correct answer is E.

Endothelial cells line the vast majority of vascular channels, and with the exception of small lymphatics, sinuses, and sinusoids, also contain a peripheral layer of pericytes or smooth muscle cells. Endothelial cells express the so-called vascular markers CD31, CD34, von Willebrand factor, and Ulex europaeus lectin-1. Pericytes and smooth muscle cells contain contractile proteins (smooth muscle actin and α-smooth muscle actin). Lymphatic endothelial cells express lymphatic vascular endothelial hyaluronan receptor-1 (LYVE-1) and podoplanin (D2-40). Activated blood endothelial cells may, however, weakly express these two markers. Small lymphatics lack pericytes, and larger ones demonstrate irregular media made of smooth muscle cells.

There is undoubtedly considerable heterogeneity of endothelial and smooth muscle cell phenotypes and functions in normal vessels that remain poorly understood. It is certain that there are specialized functions of endothelial cells, including antigen presentation, secretion of cytokines, and so on, beyond the simple and obvious properties of maintenance of blood or lymph circulation. Veins lack an internal elastic lamina.

Which of the following histopathologic features is NOT associated with vascular malignancy?

A) Small round vessels in a lobular distribution with flat endothelial cells containing inconspicuous nucleoli.

B) Prominent anastomosing angular vascular channels with plump endothelial cells containing conspicuous nucleoli.

C) Angular vessels lined by compact endothelial cells that exhibit multilayering or “piling up” on one another.

D) Solid areas composed of polygonal and/or spindled endothelial cells with intracytoplasmic lumina containing red blood cells

E) Irregular angulated vessels extending into the subcutis with intraluminal papillary growth and endothelial tufting.

The correct answer is A.

Benign vascular lesions may be either true neoplasms that arise postnatally or vascular malformations that are present at birth. Although by definition vascular malformations are present at birth, they may not manifest clinically until later in life. In regard to histopathology, benign lesions have a relatively circumscribed architecture with rounded or rounded and linear ...

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