Pathology and Diagnosis - Myoepithelial cells can be spindled, plasmacytoid, epithelioid, or clear. - Tubules or epithelium are absent or present in a small amount (5%) by definition. - Tumors with myoepithelial cells and a large amount of tubules are classified as pleomorphic adenomas. - Pleomorphic adenomas must contain the characteristic chondromyxoid stroma, which is normally absent in myoepithelioma. - The absence of tubules and chondromyxoid stroma helps differentiate myoepithelioma from pleomorphic adenoma. - Myoepitheliomas are diagnosed through examination of the tissue by a pathologist. - Diagnosis can be confirmed through low magnification examination. - High magnification examination may be necessary for accurate diagnosis. - Histopathological features specific to myoepithelioma aid in diagnosis. - Immunohistochemical staining can be used to support the diagnosis.

Treatment - Benign myoepitheliomas are treated with simple excision. - They have a lower recurrence rate compared to pleomorphic adenomas. - Malignant myoepitheliomas are also excised. - In the past, dacarbazine has been used for treatment of malignant myoepitheliomas. - Malignant myoepitheliomas are prone to both metastasis and recurrence.

Related Entities - Pleomorphic adenoma is closely related to myoepithelioma. - Ectomesenchymal chondromyxoid tumor is another related entity. - Both pleomorphic adenoma and ectomesenchymal chondromyxoid tumor have distinct features distinguishing them from myoepithelioma. - Understanding these related entities helps in accurate diagnosis. - Comparative analysis of these entities contributes to the understanding of their pathogenesis.

References - Barnes, L., Appel, BN., Perez, H., El-Attar, AM. (Jan 1985). Myoepithelioma of the head and neck: case report and review. Journal of Surgical Oncology, 28(1), 21–8. - Wu, Tao; Lao, Zhiwei; Tang, Jun (1 January 2014). Myoepithelial carcinoma of the head and neck: A report of 23 cases and literature review. Cancer Treatment Communications, 2(2–3), 24–29. - Smith BC, Ellis GL, Meis-Kindblom JM, Williams SB (May 1995). Ectomesenchymal chondromyxoid tumor of the anterior tongue. Nineteen cases of a new clinicopathologic entity. American Journal of Surgical Pathology, 19(5), 519–30. - These references provide further insights into the characteristics, diagnosis, and treatment of myoepithelioma. - They contribute to the existing literature and research on this topic.

Notable Points - Pleomorphic adenomas must contain the characteristic chondromyxoid stroma, which is normally absent in myoepithelioma. - Myoepitheliomas have a lower recurrence rate compared to pleomorphic adenomas. - Malignant myoepitheliomas are prone to both metastasis and recurrence.