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RACS ASC 2026
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A rare case of myoepithelioma in buccal mucosa
Poster
Presentation Description

Institution: Royal Melbourne Hospital - Victoria, Australia

A 64-year-old non-smoking woman was referred with a painless 1 x 1.5 cm right buccal mucosal mass, present for several years. Initial biopsy revealed a myoepithelial lesion with atypical features concerning for low-grade malignancy. She underwent a wide local excision; intraoperatively, the lesion was confined to the buccal mucosa and although near, did not involve the right parotid duct. Definitive histopathology favoured myoepithelioma, supported by positive immunohistochemistry for calponin and epithelial membrane antigen(EMA). There was no infiltrative growth, significant atypia or necrosis to suggest myoepithelial carcinoma. No salivary tissue was identified. The closest deep margin was <0.1mm but otherwise clear. Multidisciplinary review recommended clinical surveillance. Myoepitheliomas are rare salivary gland tumors, accounting for 1.5% of all glandular neoplasms [1]. Soft tissue myoepitheliomas are even rarer and typically arise in the trunk or extremities. They can be differentiated from pleomorphic adenomas by lack of a chondromyxoid matrix and epithelial cells [1]. Immunohistochemical staining is positive for cytokeratin, EMA, and S-100 protein [2]. Differentiation from myoepithelial carcinoma relies primarily on lack of significant cytologic atypia, but low mitotic activity and absence of significant necrosis support diagnosis [2]. This case highlights the rarity of myoepitheliomas in the head and neck, which can be difficult to distinguish from pleomorphic adenomas or myoepithelial carcinomas. Accurate diagnosis may require surgical resection to provide sufficient histopathology, which needs to be correlated with immunohistochemistry and clinical features to guide appropriate management. References [1] Karthik R, et al. Myoepithelioma. J Pharm Bioallied Sci. 2015. [2] Jo VY, Fletcher CDM. Myoepithelial neoplasms of soft tissue. Head Neck Pathol. 2015;9:32–38.
Presenters
Authors
Authors

Dr Olivia Lin - , Dr Richi Jiang - , Dr Anton Sklavos - , Dr Felix Sim -