PMC4868929_01
Extraoral presentation of the lesion (case 1).
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F1
A 26-year-old male patient presented with a painful 2 x 3 cm sized extraoral swelling over the right side of the face close to the lower border of the mandible that was clinically diagnosed as an abscess (fig. 1).
A tumour composed of spindle cells showing a fascicular arrangement (case 1). HE. x20.
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F2
The haematoxylin and eosin (HE)-stained section revealed an unencapsulated tumour composed of spindle cells with indistinct cytoplasmic borders and arranged into packed short fascicles (fig. 2).
Focal EMA positivity in the tumour (case 1). x20.
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F3
Out of all the immunohistochemical investigations performed, tumour cells were strongly positive for vimentin, while focal positivity was observed with EMA (fig. 3).
PMC4868929_02
Intraoral presentation of the lesion (case 2).
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F4
Intraorally, an exophytic growth with ulceration, 3.5 x 2 cm in size, with everted, irregular margins was found on the right side of the upper buccal sulcus extending into the palatal mucosa (fig. 4).
A tumour composed of spindle cells arranged into fascicles (case 2). x10.
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F5
An undifferentiated cell component consisting of individual cells was also identified close to the non-dysplastic surface epithelium (fig. 5, 6).
Note the undifferentiated cell component present close to the non-dysplastic surface epithelium (case 2). x20.
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F6
An undifferentiated cell component consisting of individual cells was also identified close to the non-dysplastic surface epithelium (fig. 5, 6).
CK19 positivity in the undifferentiated cell component (case 2). x20.
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F7
Immunohistochemical stains for CK19 (fig. 7), EMA, BCL-2 and CD99 were positive in tumour cells while SMA, S-100, and desmin were negative in tumour cells.
MIB-1 activity of the tumour cell component (case 2). x10.
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F8
MIB-1 staining revealed a high proliferative index (fig. 8).