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Review
. 2021 Mar;14(1):67-73.
doi: 10.1016/j.path.2020.09.008. Epub 2021 Jan 5.

Myoepithelial Carcinoma

Bin Xu  1 , Nora Katabi  2
Affiliations
Review

Myoepithelial Carcinoma

Bin Xu et al. Surg Pathol Clin. 2021 Mar.

Abstract

Myoepithelial carcinoma (MECA) may overlap histologically with other salivary gland neoplasms, especially pleomorphic adenoma. MECA is characterized by cellular, uniform growth of myoepithelial cells and multinodular expansile invasive pattern with zonal cellular distribution. It may arise de novo or in association with pleomorphic adenoma (myoepithelial carcinoma ex pleomorphic adenoma). By immunohistochemistry, MECA is positive for cytokeratins and at least one of the myoepithelial markers, including S100. PLAG1 fusion is the most common genetic alteration. Carcinoma ex pleomorphic adenoma and necrosis correlate with worse clinical outcome in MECA, and necrosis can be used to stratify MECA as high grade.

Keywords: Carcinoma ex pleomorphic adenoma; Myoepithelial carcinoma; PLAG1; Pleomorphic adenoma.

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Conflict of interest statement

Disclosure The authors have nothing to disclose. Research reported in this publication was supported in part by the Cancer Center Support Grant of the National Institutes of Health/National Cancer Institute under award number P30CA008748. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Figures

Figure 1.
Figure 1.. Cytologic features of MECA.
MECA can exhibit a mixture of cell types A: Spindle cells. B: Clear cells. C: Plasmacytoid cells. D: Epithelioid cells. MECA: Myoepithelial carcinoma.
Figure 2.
Figure 2.. Histologic features of MECA.
A: MECA is characterized by uniform proliferation of myoepithelial cells with multinodular invasive pattern. B: Zonal cellular distribution with cellular periphery (P) and hypocellular (C) center is a common characteristic feature of MECA. C: Necrosis (N) correlates with worse outcome and can be used to identify high grade MECA. MECA: Myoepithelial carcinoma.
Figure 3
Figure 3. Immunohistochemistry in MECA.
A: MECA is positive for keratin. B: S100 is positive in the majority of MECA. C: Calponin staining in MECA. D: PLAG1 showing nuclear staining in myoepithelial cells. MECA: Myoepithelial carcinoma.
Figure 4
Figure 4. Differential diagnoses of MECA.
(A-B) MECA ex PA. The nodular expansile invasive pattern with hypercellular peripheral rim (P) and hypocellular center (C) in MECA ex PA help to differentiate MECA from PA. (B) PA component of MECA ex PA (high power picture of the black box in A). (C) PA: The typical heterogenous distribution of ducts (D), myoepithelial cells (M) and Stroma (S) in PA. (D) EMC showing ductal cells surrounded by clear myoepithelial cells. MECA: Myoepithelial carcinoma. PA: pleomorphic adenoma. MECA ex PA. Myoepithelial carcinoma ex pleomorphic adenoma. EMC: Epithelial myoepithelial carcinoma.
See this image and copyright information in PMC

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