PMC3421480_01
Intraoral findings. A physical examination found a painless, non-tender, elastic hard, smooth mass that was covered by intact oral mucosa and not fixed to the mandible. Arrows: tumor.
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The mass was covered by intact oral mucosa and it was not fixed to the surrounding structures, including the mandible (Figure 1).
MR images. MR images showing a well-circumscribed mass lesion located in the right sublingual space. Arrows: tumor. (a) T1 weighted image. (b) T2 weighted image. (c) Enhanced T1 weighted image.
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In a magnetic resonance (MR) examination, a space occupying mass lesion, which showed homogeneous low signal intensity on T1-weighted images and homogeneous intermediate signal intensity on T2-weighted images, was delineated (Figure 2).
Fat suppressed dynamic enhanced MR images. Fat suppressed dynamic enhanced MR images showing gradually enhanced mass lesion located in sublingual space. (a) Precontrast image. (b-e) Early phase images. (f) Delayed image.
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On dynamic MR images, tumor located in sublingual space was gradually enhanced as compared to that of surrounding sublingual glands (Figure 3).
The cut surface of the resected specimen showed a grayish white, homogeneous, and solid mass without bleeding foci or necrotic areas. (a) Gross appearance. (b) Cut slice of the resected specimen.
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The cut surface showed a grayish white, homogeneous, solid mass with no bleeding foci or necrotic areas (Figure 4).
Histopathological features of the resected specimen. (a) The tumor was composed of a pleomorphic adenoma that consisted of myxoid, chondroid, and mucoid materials. (b) There was a rupture of the fibrous capsule and tumor cells had slightly invaded the surrounding fat tissues. (c, arrows) Diffuse cell-rich sheets composed of myoepithelial cells with round nuclei were seen, among which there were atypical cells and (d, arrowhead) mitotic figures. Hematoxylin and eosin staining; magnification: a, x 6.6. b, x 13.2. c,d x 132.
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Histopathological examination revealed that the tumor was composed of a pleomorphic adenoma consisting of myxoid, chondroid and mucoid materials, as well as duct-like structures and cell-rich mesenchymal tissues (Figure 5a). Although it was well encapsulated, there was a rupture of the fibrous capsule and tumor cells had slightly invaded the surrounding fat tissues (Figure 5b). Diffuse cell-rich sheets composed of myoepithelial cells with round nuclei were also seen, among which there were mitotic figures and atypical cells (Figure 5c and 5d).
Immunohistochemical staining of the resected specimen. (a, x 66) Tumor cells expressed reactivity with antibodies to SMA and (b, x 66) duct like cells were positive to cytokeratin.
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The cells that composed of cell-rich sheets were positive to smooth muscle actin (Figure 6).