Oncocytic variant of epithelial-myoepithelial carcinoma of the parotid gland: a rare case report and review of the literature

Abstract Introduction Oncocytic variants of epithelial-myoepithelial carcinoma are exceptionally rare and often difficult to distinguish from other oncocytic or biphasic salivary tumors. This case underscores the diagnostic challenge and highlights the importance of detailed histopathological and immunohistochemical evaluation for accurate classification. Case presentation A 71-year-old woman presented with a slowly enlarging mass in the superficial lobe of the parotid gland. Imaging demonstrated a well-circumscribed lesion. The patient underwent superficial parotidectomy. Histopathological examination revealed biphasic epithelial and myoepithelial cell differentiation with prominent oncocytic changes. Immunohistochemistry showed CK7 positivity in the ductal epithelial component and p63 and calponin positivity in the myoepithelial layer, confirming the diagnosis of oncocytic variant EMCa. Clinical discussion Oncocytic EMCa is a particularly rare subtype and may resemble intraductal carcinoma, pleomorphic adenoma, or other oncocytic neoplasms. Accurate diagnosis requires combined evaluation of morphology and specific immunohistochemical markers. The distinction is critical because oncocytic EMCa generally demonstrates indolent behavior but requires complete excision and close follow-up. This case underscores the value of appropriate IHC panel selection and correct classification to guide management. Conclusion This case illustrates the diagnostic challenges posed by oncocytic EMCa and emphasizes that careful integration of morphology with targeted immunohistochemistry is essential for accurate diagnosis and clinical decision-making.