Yonsei Med J.  2005 Oct;46(5):710-714. 10.3349/ymj.2005.46.5.710.

A Case of Soft Tissue Myoepithelial Tumor Arising in Masticator Space

• Go JH

• KMID: 2158154
• DOI: http://doi.org/10.3349/ymj.2005.46.5.710

Abstract

Soft tissue myoepithelial tumors of the head and neck region are very rare, and only one case of soft tissue myoepithelial tumor occurring in the masticator space has been reported in the world literature. A case of soft tissue myoepithelial tumor with benign histomorphology, but with an invasive growth pattern, occurred in the masticator space of a 46-year- old male patient. Magnetic resonance imaging of paranasal sinus/nasopharynx revealed a well-defined, lobulated heterogeneous mass with high signal intensity and dense calcification in the masticator space between the left mandible ramus and pterygoid process. Grossly, the tumor was a well- circumscribed ovoid solid mass and consisted of yellowish gray glistening firm tissue. Histologically, the tumor showed a multinodular growth pattern and consisted of epithelioid cells in chondromyxoid stroma and of spindle-shaped to ovoid cells in the hyaline stroma. The tumor cells appeared bland, and no mitosis or necrosis was found within the tumor. The tumor focally invaded to adhered bone tissue. Immunohistochemically, the tumor cells were diffusely positive for epithelial membrane antigen, smooth muscle actin, but negative for other epithelial markers. Ultrastructurally, the cytoplasm of the tumor cells contained sparse microfilaments and subplasmalemmal densities. Attenuated desmosomes were commonly seen between the tumor cells.

Keyword

Soft tissue; myoepithelial; masticator space; clinical

MeSH Terms

Stomatognathic Diseases/*pathology
Soft Tissue Neoplasms/*pathology/ultrastructure
Myoepithelioma/*pathology/ultrastructure
Middle Aged
Microscopy, Electron
Male
Immunohistochemistry
Humans

Figure

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  Fig. 1 MR PNS nasopharynx revealed a well-defined, lobulated, heterogeneous mass with high signal intensity in the masticator space.

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  Fig. 2 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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  Fig. 3 Immunohistochemically, the tumor cells were focally positive for EMA (A) and diffusely positive for smooth muscle actin (B).

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  Fig. 4 Electron microscopic examination revealed cytoplasmic microfilaments and subplasmalemmal densities (×9000) (A) and attenuated desmosomes (×15000) (B).

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