Proton beam therapy and chemotherapy for Myoepithelial carcinoma ex pleomorphic adenoma of palate: A report of a rare case and literature review

Abstract

Myoepithelial carcinoma ex pleomorphic adenoma (MECA-exPA) is an extremely rare malignant neoplasm. Most MECA-exPA cases occur in the parotid gland and rarely in the minor salivary glands. Although the currently accepted treatment is complete surgical resection with clear margins, there is no collective opinion on the benefit of adjuvant therapies such as radiation therapy or chemotherapy, due to its extreme rarity. Here, we report a case of MECA-exPA of the palate. A 73-year-old male patient with a medical history of pleomorphic adenoma of the palate was referred to our department with a palatal tumor. Pathological examination of the biopsy specimen revealed a diagnosis of pleomorphic adenoma. The patient refused treatment and returned to our department four years later with an enlarged palatal tumor. Pathological examination of the biopsy specimen again revealed a diagnosis of pleomorphic adenoma. The patient underwent tumor resection under general anesthesia, and the resection margin was set at 5mm. The pathological diagnosis was MECA-exPA, and pathological examination revealed a positive surgical margin. The patient received proton beam therapy (PBT) and chemotherapy, with cisplatin as adjuvant therapy. There has been no recurrence or metastasis for three years and eight months after the completion of adjuvant therapy. To our knowledge, this is the first report of PBT and chemotherapy for MECA-exPA of the palate. Surgery for MECA-exPA, chemotherapy with cisplatin, and PBT as adjuvant therapy may improve patient survival. However, further case series and clinical studies are needed.