Cases reported "Myoepithelioma"

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1/12. Mixed tumors, myoepitheliomas, and oncocytomas of the soft tissues are likely members of the same family: a clinicopathologic and ultrastructural study.

    Four diagnostically unusual soft tissue tumors are presented. All lesions were of consistent size and long duration. Histologically, one lesion was analogous to mixed tumors of the usual sites (i.e., salivary glands), one lesion was totally spindled, and the two other lesions both had oncocytic appearances (epithelioid and spindle biphasic pattern in a case, purely epithelioid in the other). Immunohistochemically, the mixed tumor was positive for vimentin, cytokeratins, S-100 protein, and focally for EMA. The purely spindled tumor exhibited immunoreactivity for vimentin, actins, S-100 protein, EMA (focally), and GFAP. The oncocytic biphasic tumor was positive for mitochondrial antigen, vimentin, and actins. The purely epithelioid oncocytic neoplasm was immunoreactive only for mitochondrial antigen and vimentin. Ultrastructurally, in the epithelial-like portion of the first (mixed) tumor, peripheral arrays of contractile filaments were detected along with well-developed desmosomes. In the second (spindled) case, peripheral contractile filaments and attenuated desmosomes were also seen. In the third case, a huge number of mitochondria, some desmosomes, and actin-type microfilaments were found. In the fourth case, desmosomes and punctate subplasmalemmal densities, in addition to numerous mitochondria, were documented. In all cases an external basal lamina were present, which was discontinuous in the first three cases and almost continuous in the fourth. These tumors were respectively designated as mixed tumor, myoepithelioma of the classic type, myoepithelioma of oncocytic type with biphasic cell architecture, and true oncocytoma. So far, all tumors have followed benign clinical courses (median follow up: 12 months). Comparisons with similar tumors of other sites are drawn, and suggestions for considering all of them as members of the same myoepithelial-derived tumor family are given.
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2/12. Multifocal, nascent, and invasive myoepithelial carcinoma (malignant myoepithelioma) of the breast: an immunohistochemical and ultrastructural study.

    This report describes the light microscopic (LM), immunohistochemical (IHC), and electron microscopic (EM) features of a multifocal, nascent, and invasive myoepithelial carcinoma of the breast. By LM, the spindle cells disclosed fibrillar acidophilic cytoplasm, mild nuclear atypia, and a low mitotic index. Myoepithelial differentiation was established through IHC (single- and double-labeling techniques) and EM: periductal and infiltrating spindle cells coexpressed total muscle actin, alpha-smooth muscle actin, vimentin, cytokeratin 14, and pankeratin, and their EM features were characteristic of myoepithelial cells, i.e., perinuclear tonofilaments, subplasmalemmal bundles of microfilaments with dense bodies, intermediate junctions, poorly developed desmosomes, pinocytic vesicles, and fragmented external lamina. No invasive epithelial cells disclosed luminal differentiation (by LM, IHC, EM), identifying, thus, this neoplasm as a pure spindle cell myoepithelial carcinoma of the breast.
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3/12. A case of soft tissue myoepithelial tumor arising in masticator space.

    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.
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4/12. Myoid gonadal stromal tumor with epithelial differentiation (? testicular myoepithelioma).

    A 46-year-old man presented with a cytologically bland testicular tumor composed of spindle cells that showed both epitheliallike (ie, true desmosomes and tonofilamentlike structures) and myogenous differentiation (ie, thin filaments with focal densities and alpha-smooth muscle actin immunoreactivity). Tumor cells were immunoreactive for vimentin and S-100 protein but negative for cytokeratin and desmin. Peritubular myoid cells are present in the normal testis; contain subplasmalemmal micropinocytotic vesicles; show thin filaments with focal densities; and are reactive with desmin, vimentin, and alpha-smooth muscle actin. They have no desmosomes and lie outside the basement membrane of the seminiferous tubules; thus they are not true myoepithelial cells (a cell type not present in the testis). Paradoxically, the current tumor appeared to show bidirectional differentiation, mimicking both a peritubular myoid spindle cell and an epitheliallike cell (possibly similar to the granulosa cell or rete testis epithelial cell). Although the findings suggest myoepithelial differentiation, the cytogenesis of this tumor remains uncertain.
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5/12. Myoepithelioma. review of the literature and report of a case with ultrastructural confirmation.

    The myoepithelioma is a rare salivary gland tumor composed nearly exclusively of myoepithelial cells. A case occurring on the palate of a 22-year-old man is reported. Electron microscopic findings of occasional desmosomes, a basal lamina associated with the plasma memb;rane, and perinuclear cytoplasmic filaments confirmed the diagnosis. The myoepithelioma appears to resemble the pleomorphic adenoma clinically and may be a development variant of the pleomorphic adenoma.
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6/12. Malignant myoepithelioma (myoepithelial carcinoma) of the breast: an ultrastructural and immunocytochemical study.

    This report describes the light (LM) and electron microscopic (EM) features and the results of an indirect immunofluorescence study (IF), the latter using monoclonal and monospecific antibodies to cytoskeletal proteins, of a malignant, invasive and metastatic breast myoepithelioma. A 53-year-old female underwent mastectomy for a large necrotic mammary tumor that had invaded the overlying skin. By LM, the neoplasm was composed of interlacing bundles of large, elongated and interspersed stellate cells with acidophilic cytoplasm. The neoplastic cells displayed a moderate degree of anaplasia, high mitotic activity, and strong tendency for necrosis. Stromal desmoplasia was marked, especially toward the center of the neoplasm. By IF, the tumor cells revealed bright cytoplasmic fluorescence with antibodies to actin, prekeratin, and cytokeratin. A few scattered spindle cells, which stained with the anti-vimentin and anti-actin anti-bodies, most likely represented stromal myofibroblasts. The anti-desmin reaction was negative. By EM, the neoplasm was composed of variably differentiated, elongated and stellate myoepithelial cells connected by desmosomes, enveloped by remnants of basal lamina, and containing pinocytotic vesicles, a well-developed rough endoplasmic reticulum, large Golgi areas, aggregates of intermediate filaments that were often arranged in dense curvilinear bundles (tonofilaments), and bundles of microfilaments with fusiform, dense bodies. The combined LM, EM, and IF study of this mammary tumor establishes its myoepithelial origin and, thus, identifies it as myoepithelial carcinoma distinct from other spindle cell breast tumors. This neoplasms was locally invasive and cytologically malignant; moreover, its malignancy was further confirmed by the development of lung and pleural metastases.
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7/12. Myoepithelioma of the breast: histologic, immunologic, and electromicroscopic appearance.

    This report describes the histologic, immunologic, and ultrastructural features of a distinctive spindle-cell tumor of the female breast interpreted as pure myoepithelioma. By light microscopy, the tumor showed the mammary parenchyma replaced by bundles of fusiform cells, which cytoplasms contained myosin and actin, demonstrated immunologically. Ultrastructurally, the spindle cells were joined by mature desmosomes and presented parallel bundles of microfilaments and remnants of basal lamina.
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8/12. Infiltrating myoepithelioma of the breast.

    This report describes the histologic and ultrastructural features of a spindle cell myoepithelioma arising in the breast of a 60-year-old woman. By light microscopy, the tumor consisted of interlacing bundles of elongated cells sometimes arranged in a storiform pattern. No intraductal or invasive carcinoma was identified. Ultrastructurally, the neoplasm was composed of activated, differentiated myoepithelial cells showing evidence of squamous metaplasia, i.e., spindle-shaped cells joined by mature desmosomes and encompassed by remnants of basal lamina containing a well-developed rough endoplasmic reticulum, pinocytotic vesicles, prekeratin filaments, and longitudinally oriented bundles of microfilaments with fusiform densities. Numerous cisternae of rough endoplasmic reticulum suggested heightened metabolic activity, whereas the presence of cytoplasmic prekeratin filaments indicated squamous metaplasia. The cells comprising most previously reported "myoepitheliomas" examined by electron microscopy lacked many of the distinctive fine structural features of the normal myoepithelial cell. At present, the diagnosis of myoepithelioma should be based on strict ultrastructural criteria. The clinical behavior of this particular lesion in the breast is unknown. If the tumor follows the course of comparable salivary gland neoplasms, the likelihood of systemic spread is low. Primary therapy for a tumor proven to be an infiltrating myoepithelioma of the breast should be directed at complete excision of the lesion.
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9/12. Myoepithelial carcinoma of the breast with distant metastasis and accompanied by adenomyoepitheliomas.

    A breast tumour in a 47-year-old female with axillary lymph node metastasis was interpreted as the rare malignant adenomyoepithelioma based on morphological and immunohistochemical studies. Multiple bone metastases developed and the patient died after 7 months. The malignant neoplasm consisted of cords and interlacing bundles of spindle cells with indistinct cell borders and clear cytoplasm. The cells stained positively for cytokeratin, S-100 protein, GFAP, and muscle-specific actin, and possessed basal lamina, pinocytic vesicles, tonofilaments, desmosomes, and intermediate filaments with dense bodies. In some areas, cells with microvillous projections enclosed small spaces. In the breast, foci of myoepithelioma with various morphological subtypes and infiltration coexisted, demonstrating the origin of the malignant tumour. The histogenesis of the myoepithelial tumours is discussed.
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10/12. Immunohistochemical and ultrastructural study of malignant plasmacytoid myoepithelioma of the maxillary sinus.

    Myoepithelioma is a rare salivary gland tumor which is composed exclusively of myoepithelial cells. Histologically, it can be divided into three cell types: spindle, plasmacytoid and mixed type. Malignant myoepithelioma is characterized by invasive growth. In March 1995, a 60-year-old man presented with a left cheek tumor which he had first noted 2 years previously. Computed tomography revealed a large expansile tumor in the maxillary sinus with invasion into the surrounding soft tissue. Partial resection of the tumor was performed because of extensive involvement of the surrounding tissue. The patient died due to spread to the brain 5 months after surgery. Histologically, the tumor was composed exclusively of plasmacytoid cells, with bone destruction. Immunohistochemically, these cells were negative for immunoglobulin light chains (kappa and lambda) and heavy chains (Ig G, A, M) but positive for S-100, cytokeratin, actin and vimentin.Ultrastructurally, the tumor cells contained numerous randomly oriented actin-like microfilaments in the cytoplasm, and had desmosomes on the cell membrane. Malignant plasmacytoid myoepithelioma of the maxillary sinus was diagnosed. In addition to our case, only five cases of pure plasmacytoid myoepithelioma have been reported. Plasmacytoid myoepithelioma tends to occur in the minor salivary glands and has more aggressive behavior than spindle cell myoepithelioma. Morphologically, it is very difficult to differentiate plasmacytoid myoepithelioma from plasmacytoma and immunohistochemical staining is necessary to make a correct diagnosis.
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