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Keratin
Published in Masahiko Mori, Histochemistry of the Salivary Glands, 2019
Histologically, myoepithelial tumor cells are divided into two types: plasmacytoid or hyalin cells (Figure 31 a), and fibrous cells. Both tumor cells may be distributed singly or mixed. Immunohistochemical studies of myoepithelial cells of salivary gland tumors reveal several distinguishing markers including intermediate filament proteins, contractive proteins, and others.80–85 Myoepithelial cells have been identified with phosphotungstic acid hematoxylin (PTAH) and iron hematoxylin (IH). The light microscopic and ultrastmctural studies of myoepithelial cell tumors by several authors have suggested modified and neoplastic myoepithelial cells to be the cell of origin.86–90 The incidence of myoepithelioma cells in pleomorphic adenomas has varied. Hyaline cells were found in 38% of minor salivary glands (52 cases), 21% in major glands (72 cases).91 Seventy percent of the cases (23 cases) were of spindle-cell type, 17% were composed of plasmacytoid cells, and 13% had both cell types.92 Neoplastic epithelial cells regularly stained for KL1 and K8.12, whereas they showed a slight to negative reaction for PKK1 and other monoclonals (Figure 31 b, c, d). The histochemical expression for keratin proteins in neoplastic myoepithelial cells was essentially the same as those in modified myoepithelial cells of pleomorphic adenomas. Small tumor cell type (Figure 31 e) or clear cell type myoepithelioma cells stained positively for keratin (KL1, K8.12) and coexpressed to keratin (K8.12) and vimentin.
Head and neck
Published in Tor Wo Chiu, Stone’s Plastic Surgery Facts, 2018
Myoepithelioma is a tumour of minor salivary glands that is similar to PA, though much less common (1% of all salivary gland neoplasms) usually presenting as a large intra-oral swelling with a characteristic slow growth over many years. It is usually said that biopsy should be avoided; MRI defines tissue planes and resectability. Treatment may not be required, though secondary middle ear obstruction and effusion may require grommet insertion.
Pulmonary Mesenchymal Tumor
Published in Dongyou Liu, Tumors and Cancers, 2017
According to the 2015 WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart, mesenchymal tumors arising from the lung (i.e., pulmonary mesenchymal tumors) include pulmonary hamartoma, chondroma, PEComatous tumors (lymphangioleiomyomatosis, PEComa [benign/clear cell tumor]; PEComa malignant), congenital peribronchial myofibroblastic tumor, diffuse pulmonary lymphangiomatosis, inflammatory myofibroblastic tumor, epithelioid hemangioendothelioma, pleuropulmonary blastoma, synovial sarcoma, pulmonary artery intimal sarcoma, pulmonary myxoid sarcoma with EWSR1–CREB1 translocation, and myoepithelial tumors (myoepithelioma, myoepithelial carcinoma) [1].
Myoepithelioma of bone: ultrastructural, immunohistochemical and molecular study of three cases
Published in Ultrastructural Pathology, 2019
Paweł Kurzawa, Martin K. Selig, Patryk Kraiński, Michał Dopierała, G. Petur Nielsen
Myoepithelial cells of salivary glands account for the myxomatous and chondroid substances like acid glycosaminoglycans: hyaluronic acid, heparin sulfate, chondroitin-4-sulfate, chondroitin-6-sulfate deposited in the stroma as well as basal membrane components: elastin and tenascin.35–37 However, according to Shah et al.34, neoplastic myoepithelial cells change the amount and the nature of the substances produced. Herein, the background in case 1. was myxoid and collagenous, which was like the background produced by myoepithelial cells in salivary glands, a feature also identified by Franchi et al. in primary juxtacortical myoepithelioma/mixed tumor of the bone. The neoplastic cells in case 1 actively produced the collagen matrix, whereas the cells in cases 2 and 3 did not appear to. Cases 2 and 3 showed a sparse collagenous and sometimes flocculent background, while basal lamina was present only in case 1 which may be a characteristic of well-differentiated cells. However, lack of basal lamina may not necessarily be a consistent feature as Alberghini et al.31 described its presence in their case of malignant myoepithelioma of the bone.
Atypical presentation of invasive myoepithelioma in a pediatric patient
Published in Orbit, 2022
Angela Y. Chang, Ann Q. Tran, William Plum, Andrea A. Tooley, Sonya Purushothaman, Michael Kazim
Myoepithelioma (ME) is a rare, monomorphic adenoma of epithelial cell origin most commonly observed in the salivary glands.1 Typically, MEs arise from myoepithelial cells surrounding glandular tissue but can also be of soft tissue origin.2 In the periocular region, MEs of the lacrimal gland have rarely been described.1,3–8 Less frequently, MEs have been observed as primary lesions in the orbit,2,9,10 such as metastatic lesions,11 and in the eyelid, thought to be derived from ectopic lacrimal tissue.12 MEs of the lacrimal gland are generally benign but malignant transformation has been described.6,7 Complete excision of ME is curative, with no reported recurrences.12