Epithelial-Myoepithelial Carcinoma of the Submandibular Gland Arising from Recurrent Pleomorphic Adenoma: A Rare Case Report

A 36-year-old male with a history of smoking presented with recurrent right submandibular swelling. Initially diagnosed with pleomorphic adenoma, he underwent total submandibulectomy. After 2 years, he developed a recurrent submandibular mass. Clinical and imaging assessments revealed a 6.2 cm multinodular tumor without invasion of adjacent structures. Surgery under general anesthesia involved tumor resection and lymph node dissection. Pathology confirmed carcinoma ex pleomorphic adenoma, specifically epithelial-myoepithelial carcinoma (EMC). Despite focal necrosis and a tumor size of 10.8 cm, margins were clear, and no lymph node metastasis was detected (pT3N0). Postoperative imaging showed no recurrence or metastasis, and the patient remains disease-free at the 25th month. This case highlights the diagnostic and therapeutic complexities of EMC, a rare malignancy constituting <1% of salivary gland tumors. Multidisciplinary collaboration enabled accurate diagnosis and effective treatment. Early intervention in recurrent pleomorphic adenomas is crucial to mitigate malignant transformation risk. Long-term surveillance is essential due to EMC's potential for late recurrence.