PMC2836790_01
A dark-red-colored tumor, measuring approximately 1 cm in diameter, that was tender and smooth, with a clear boundary being seen in the left side of the lower lip (inside white circle).
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fig1
Clinical intraoral examination of the left side of the lower lip showed a tender, smooth mass measuring approximately 1 cm in diameter without discoloration reaction (Figure 1).
(a) Axial T1-weighed MR image of the lesion (inside yellow circle). This image shows that the margin of the lesion showed an enhanced line with no signal area in the center of the lesion (arrow). TR was 542 (milliseconds) and TE was 9 (milliseconds). The sequence of MR image was FSE, and NEX was 512 x 512. (b) Axial T2-weighed MR image of the lesion (inside yellow circle). This image shows a no signal intensity area in the center of the lesion and also a no signal intensity area beside two low-signal intensity dots (arrows). TR and TE parameters of T2 weighed MR image were 3000 (m sec) and 80 (m sec). The sequence of MR image was FSE, and NEX was 512 x 512.
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fig2
In an axial T1 weighed MR image, the marginal edge of the lesion showed an enhanced line with the center of the lesion showing zero signal intensity (Figure 2(a)). T2-weighed MR image, the side edge of the lesion showed a high-signal intensity area and the inside of the lesion also showed a no signal-intensity area next to two low-signal-intensity dots (Figure 2(b)). The MR image mimicked a hemangioma.
(a) A thrombus (inside green circles) was observed in the expanded blood vessels (blue arrows) with venous pool (yellow arrows) using hematoxylin-eosin staining (Original magnification, x3.2; Bar, 1000 micro meter). (b) The figure shows the area inside the black square of Figure 2(a). Proliferated endothelial papillary cells were observed. Expanded elastic fibers (yellow arrows) are present on the blood vessel surface using hematoxylin-eosin staining (Original magnification, x16; Bar, 100 micrometer).
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fig3
In addition, it was observed that the endothelial cells showed papillary proliferation (Figures 3(a) and 3(b)).
The endothelial cells of this lesion were reactive on immunohistochemical staining for CD31, and CD31 was positive in the endothelial cells (Original magnification, x16; Bar, 100 micrometer).
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fig4
The immunohistochemical examination revealed that staining for cluster of differentiation 31 (CD31) (Figure 4) and Factor VIII-related antigen (Figure 5) were positive in the endothelial cells, and staining for alpha-smooth muscle actin (alpha-SMA) was positive in the single layer of the blood vessel walls.
The endothelial cells of this lesion were reactive on immunohistochemical staining for Factor VIII related antigen, and Factor VIII related antigen was positive in the endothelial cells (Original magnification, x16; Bar, 100 micrometer).
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fig5
The immunohistochemical examination revealed that staining for cluster of differentiation 31 (CD31) (Figure 4) and Factor VIII-related antigen (Figure 5) were positive in the endothelial cells, and staining for alpha-smooth muscle actin (alpha-SMA) was positive in the single layer of the blood vessel walls.
The endothelial cells of this lesion were reactive on immunohistochemical staining for alpha-SMA, and alpha-SMA was positive in the single layer of the blood vessel walls (yellow arrows). Thin, expanded smooth muscle cells in the vessel wall (white arrows) were also observed (Original magnification, x16; Bar, 100 micrometer).
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fig6
Thin, expanded smooth muscle cells in the vessel wall were also observed (Figure 6).