Carcinoma ex-pleomorphic adenoma of the base of tongue: A case report and review of malignant minor salivary gland tumors

EDUCATIONAL OBJECTIVE: At the conclusion of this presentation, the participants should be able to demonstrate an understanding of the differential diagnosis of minor salivary gland tumors, compare the histopathologic characteristics of common tumors, explain what carcinoma ex-pleomorphic adenoma is, and discuss the treatment options and outcomes for these tumors. OBJECTIVE: To present a case of carcinoma ex-pleomorphic adenoma (CXPA) arising from the base of tongue in a 61-year-old male and to review the literature to elucidate the incidence, histopathologic characteristics, treatment, and outcomes in malignant minor salivary gland tumors. DESIGN: Case report and literature review. METHODS: The patient's medical record was reviewed and presented. A literature search of Pub Med was performed using the terms, "carcinoma ex-pleomorphic", "minor salivary tumors", and "malignant". RESULTS: The patient presented with dsyphagia and a base of tongue mass. This was confirmed on physical exam and CT of the neck. Panendoscopy and biopsy was performed with final pathology suggesting a low-grade salivary neoplasm. Operative excision was performed with a CO ₂ laser and the final pathology demonstrated CXPA with microscopic extension to the specimen margin. The patient was subsequently treated with radiation therapy. A literature review revealed that salivary gland neoplasms represent approximately 2- 3% of all head and neck malignancies with minor salivary glands accounting for 22% of these. Unlike partotid and submandibular gland tumors, the majority of minor salivary gland tumors are malignant. Adenoid cystic carcinomas and mucoepidermoid carcinomas are noted to be the most common histologic types. Surgery with or without post-operative radiation therapy is the mainstay of treatment for these carcinomas. Indicators significant to outcome include T stage, histologic type, cervical nodal or distant metastases, surgical margin status, and perineural invasion. CONCLUSIONS: Pleomorphic adenoma of the tongue base is extremely rare and to our knowledge this is the first report of CXPA of the tongue base.