PMC2810580_01
MR PNS nasopharynx revealed a well-defined, lobulated, heterogeneous mass with high signal intensity in the masticator space.
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F1
T2 weighted image) revealed a well defined, well enhancing heterogeneous mass with high signal intensity and dense calcification in the masticator space between the left mandible ramus and pterygoid process (Fig. 1). This mass measured 6 x 5.5 cm and had a lobulated margin.
Histologically, the tumor showed a multinodular growth pattern (A). The tumor was composed of epithelioid cells in the chondromyxoid stroma (B) and spindle-shaped to ovoid cells in the hyaline stroma (C). The tumor cells were cytologically bland-looking with no occurrence of mitosis.
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F2
Histologically, the tumor showed a multinodular growth pattern (Fig. 2A). The tumor was composed of epithelioid cells in chondromyxoid stroma (Fig. 2B) and of spindle-shaped to ovoid cells in the hyaline stroma (Fig. 2C).
Immunohistochemically, the tumor cells were focally positive for EMA (A) and diffusely positive for smooth muscle actin (B).
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F3
Immunohistochemically, the tumor cells were diffusely positive for epithelial membrane antigen (EMA) (Fig. 3A), but negative for other epithelial markers (Pan-cytokeratin, CAM 5.2, high MW-cytokeratin, CK 7 and CK 20). The tumor was diffusely positive for vimentin, smooth muscle actin (Fig. 3B) and focally positive for S-100 protein, but was negative for glial fibrillary acidic protein (GFAP), desmin, and CD34.
Electron microscopic examination revealed cytoplasmic microfilaments and subplasmalemmal densities (x9000) (A) and attenuated desmosomes (x15000) (B).
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F4
The cytoplasm contained sparse microfilaments and subplasmalemmal densities (Fig. 4A), and attenuated desmosomes were commonly seen (Fig. 4B).