Myoepithelial cell cartography: A review of immunohistochemical markers in salivary gland neoplasms.

Myoepithelial cells (MECs) are contractile cells that exhibit both epithelial and smooth muscle characteristics. In the salivary glands, they contribute to secretion and maintenance of glandular architecture and play a fundamental role in the development and differentiation of various neoplasms, both benign and malignant. Their involvement is particularly evident in tumors such as pleomorphic adenoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma. However, identifying MECs in tumor tissues can be challenging due to their variable morphologies and phenotypic profiles. A comprehensive literature review was performed focusing on MECs and salivary gland tumors. Immunohistochemistry has become an essential tool for MEC detection, and commonly used markers include smooth muscle actin (α-SMA) and calponin, which demonstrate good sensitivity for the contractile phenotype. S100 protein and p63 are also frequently applied, though their specificity is limited when used individually. Additional markers such as cytokeratins, GFAP, and maspin may provide complementary information, particularly in combined panels. Accurate identification of MECs through immunohistochemical profiling is essential for proper tumor classification. Therefore, this review aimed to provide a summary of the immunohistochemical markers applied for the identification of MECs and highlights the relevance of these markers in the context of salivary gland neoplasms, emphasizing the combination of different markers, given the absence of a single marker with both high specificity and sensitivity.