PMC4073474_01
(a and b) Preoperative clinical evidence with a smooth external appearance in the right side
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F1
The growth was well demarcated and it had a smooth external appearance [Figure 1a and b].
A computed tomography scan shows a non-homogeneously enhancing mass in the right parotid gland
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F2
A CT scan, performed at another center, showed a non-homogeneously enhancing mass in the right parotid gland [Figure 2].
Partial superficial parotidectomy
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F3
Under general anesthesia, partial superficial parotidectomy was performed, and a nodular, well-circumscribed mass was surgically excised with a surrounding suprafacial portion of normal parotid gland [Figure 3].
(a and b) Postoperative clinical control with evident minimal depressure
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F4
There were no signs of recurrence 24 months after the operation [Figure 4a and b].
Macroscopic appearance of the resected tumor. Grossly, the lesion was apparently well circumscribed, multilobated and gray-white in appearance; the cut surface revealed many small cysts with hemorrhagic content
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F5
Grossly, the lesion was apparently well circumscribed, multilobated and grey-white in appearance; the cut surface revealed many small cysts with hemorrhagic content [Figure 5].
The tumor was mainly composed of a population of large, polygonal clear cells of myoepithelial type arranged in sheets, nests and tubules surrounded by abundant homogeneous, eosinophilic, hyalinized stroma with small inconspicuous vessels in its context (H and E, original magnification x20)
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F6
The cells had indistinct cytoplasmic borders and were of the myoepithelial type. These cells were arranged in sheets, nests and tubules surrounded by an abundant homogeneous, eosinophilic, hyalinized stroma with small inconspicuous vessels in its context [Figure 6].
In some areas another population of cells was evident, arranged in ductal structures, surrounded by the clear myoepithelial cells; this population consisted in cuboidal eosinophilic small cells, with uniform, round nuclei, surrounding luminal spaces occupied by eosinophilic proteinaceous material (H and E, original magnification x20)
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F7
In some areas, another population of cells was evident, arranged in ductal structures and surrounded by the above-described population of cells; this population comprised small cuboidal, eosinophilic cells with uniform round nuclei surrounding luminal spaces occupied by eosinophilic proteinaceous material [Figure 7].
The myoepithelial cells were strongly reactive for p63 (p63 immunostain, original magnification x20)
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F8
Immunohistochemical evaluation revealed positivity for CKAE1/AE3 and CK7 in the small cuboidal, epithelial eosinophilic cells surrounding luminal spaces, arranged in ductal structures; the myoepithelial cells were strongly reactive for p63 [Figure 8], smooth muscle actin [Figure 9], vimentin and S-100 protein.
The myoepithelial cells were strongly reactive for smooth muscle actin (smooth muscle actin immunostain, original magnification x20)
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F9
Immunohistochemical evaluation revealed positivity for CKAE1/AE3 and CK7 in the small cuboidal, epithelial eosinophilic cells surrounding luminal spaces, arranged in ductal structures; the myoepithelial cells were strongly reactive for p63 [Figure 8], smooth muscle actin [Figure 9], vimentin and S-100 protein.