1/8. Intraductal growth of malignant mammary myoepithelioma.This report describes the histologic and immunohistologic features of an intraductal myoepithelial tumor that developed in the breast of a 61-year-old woman. Histologically, the tumor proliferated intraductally, with both a comedo or doughnut pattern and a solid pattern containing narrow fibrovascular cores, mimicking what appeared to be a conventional intraductal carcinoma. No fine papillary or arborizing growth or cribriform formation was observed. Tumor cells at the ductal peripheral zone were polygonal and clear with abundant glycogen in the cytoplasm; they were transformed into nonclear cells with slightly eosinophilic cytoplasm toward the center of the involved ducts. Occasionally, nonclear cells were elongated, with a centrally located cigar-shaped nucleus. These elongated or spindle cells tended to show a fascicular and streaming pattern similar to that of a smooth muscle tumor. Immunohistochemically, alpha smooth muscle actin (alpha-SM-actin) and S-100 protein were expressed in most of the nonclear cells. While clear cells also had a positive reaction for S-100 protein, they were mostly negative or barely positive for alpha-SM-actin. Epithelial membrane antigen (EMA) was also positive in a certain number of polygonal cells. These results support the myoepithelial nature of the present tumor, and some cells might also be immunologically differentiated into ductal epithelial cells. In addition to cytological atypia, frequent mitoses, and central necrosis within ducts, there was a minimal but evident stromal invasion, suggesting histological malignancy in this peculiar tumor.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
2/8. Spindle cell myoepithelioma of the nasal cavity.Minor salivary gland neoplasms with mesenchymal-like features are uncommon in the sinonasal tract. We herein report a case of spindle cell myoepithelioma of the nasal cavity in a 69-year-old woman who presented with a rapidly expanding tumor accompanied by episodes of epistaxis. Although initially considered as a mesenchymal neoplasm, ultrastructural and immunophenotypical characterization demonstrated its myoepithelial nature. In the sinonasal setting, this unusual neoplasm may be confused with soft tissue tumors showing spindle cell or myxoid features. Staining for cytokeratin is found to be the most useful adjunct to diagnosis.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
3/8. An epithelial and spindle cell breast tumour of myoepithelial origin. An immunohistochemical and ultrastructural study.An infiltrating epithelial and spindle cell neoplasm developed in the breast of a 63-year-old female. An excisional biopsy was performed. recurrence with rapid growth due to cyst development eventually resulted in more radical surgery. Interim fine needle aspirations had established its partially cystic nature. The unique microscopic appearance prompted the application of immunohistochemistry and electron microscopy. The tumour cells were found to exhibit characteristics denoting squamous and myoepithelial differentiation. Histopathological features of malignancy were absent. Our findings demonstrate the differentiation potential of breast epithelium. They are in concordance with the results of previous studies which delineate the histochemical and ultrastructural features of myoepithelial and establish the relationship of these cells to squamous metaplasia.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
4/8. Synchronous parotid myoepithelioma and Warthin's tumor.We present a case of an 84 yr old man who underwent resection of a slowly enlarging parotid mass. Macroscopic examination of the lesion revealed 2 distinct tumor foci which were shown histologically to be a typical Warthin's tumor with a separate tumor composed entirely of clear cells. Immunohistochemical studies of the clear cell tumor confirmed its myoepithelial nature. This is the first documented case of a coexistent Warthin's tumor and a myoepithelioma.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
5/8. Plasmacytoid myoepithelioma of the laryngeal region: a case report.The first case of plasmacytoid myoepithelioma of the laryngeal region is presented. The tumor showed immunoreactivity for the S-100 protein, low molecular weight cytokeratin, and vimentin. Staining was negative with muscular actin and glial fibrillar acid protein. By electron microscopy the tumor cells showed abundant microfibrillar material, elongated densities resembling smooth muscle dense bodies, pinocytic vesicles, and replicated basal lamina. The myoepithelial nature of plasmacytoid tumors of the salivary gland has been questioned.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
6/8. Fine-needle aspiration cytology of mammary adenomyoepithelioma: report of a case with intranuclear cytoplasmic inclusions.adenomyoepithelioma of the breast is an uncommon lesion which may recur and rarely metastasizes. We report the fine-needle aspiration (FNA) findings in one case of mammary adenomyoepithelioma in which this tumor's unusual cytomorphology led to a cytologic diagnosis of malignancy, possible metastatic to the breast. Large, atypical, polygonal cells, some with intranuclear cytoplasmic inclusions, were most worrisome cytologically, but corresponded in the biopsied specimen to cells immunohistochemically documented to be of myoepithelial origin. Nests of epithelium and myoepithelial cells sometimes embedded in fibrous, stromal fragments were suggestive of an infiltrating pattern. Recognition of such unusual features in breast FNA is most important since definitive therapy may follow an FNA diagnosis of carcinoma in some clinical settings. In cases with unusual morphology, surgical biopsy should be recommended to clarify the nature of the lesion.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
7/8. Fine needle aspiration (FNA) appearances of malignant myoepithelioma of the parotid gland.We describe the FNA features of five cases of malignant parotid myoepithelioma, the majority of which were thought clinically to be recurrent pleomorphic adenomas. A major finding was cell shape variation: round-oval, polygonal or spindle-shaped, with basophilic cytoplasm. Many were epithelial and plasmacytoid-like and had nuclear grooves, pseudoinclusions, and multinucleation. The true myoepithelial nature of the neoplastic cells was identified in all cases, but only two showed obvious cytological malignant features, both initially and on re-examination. FNA of malignant myoepithelioma may thus show overt features of malignancy, or may lack atypia and malignancy can only be identified on histology. The correct diagnosis can be predicted in FNA samples in certain cases, both in terms of typing and malignancy, whilst sometimes only the myoepithelial nature of the lesion can be assessed.- - - - - - - - - - ranking = 2keywords = nature (Clic here for more details about this article) |
8/8. Expression of smooth-muscle actin in cultured cells from human plasmacytoid myoepithelioma.OBJECTIVE: The definition of plasmacytoid myoepithelioma, a neoplasm exhibiting myoepithelial differentiation, has been recently questioned. To better understand the histogenesis of this neoplasm, we searched for myoepithelial markers in histologic sections of plasmacytoid myoepithelioma and in a cell line (M1) derived from this same neoplasm. STUDY DESIGN: Expression of vimentin, pan-keratin (AE-3) and smooth-muscle actin was studied by immunohistochemistry in paraffin-embedded tissue and by immunofluorescence in M1 cells. RESULTS: Plasmacytoid myoepithelioma tumor sections showed vimentin and AE-3 reactivity, but evidence of smooth-muscle actin was not seen. The cell line derived from this tumor also produced vimentin and cytokeratin. In addition, all cultured cells expressed smooth-muscle actin. CONCLUSION: We demonstrated that cells derived from a case of plasmacytoid myoepithelioma appear to show full myoepithelial differentiation in vitro. Thus, they are myoepithelial-like cells in nature. The lack of myogenous differentiation in vivo could be due to an inhibitory process mediated by the extracellular matrix.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |