A rare case of pleomorphic adenoma

Abstract

Pleomorphic adenoma (PA) is a benign salivary gland neoplasm. It represents 45% to 74% of all salivary gland tumors and is associated with recurrence, malignant transformation, and metastasis. The risk of malignant transformation in PA increases from around 1.6% in tumors with less than 5 years of evolution to 9.5% for those presenting for more than 15 years. Malignancies arising in PA encompass 3 entities: (1) carcinoma ex-pleomorphic adenoma (CXPA), (2) carcinosarcoma, and (3) metastasizing benign pleomorphic adenoma. CXPA is a rare, aggressive, poorly understood malignancy that usually develops in a primary or recurrent PA.

Case Description: A 65-year-old female patient reported a chief complaint of pain and swelling below the lower jaw and around her ears, for 2 years. The patient had a history of swelling at the same site 20 years prior, which was operated on 2 years ago. On clinical examination, the swelling was present on the mandibular left posterior region, extending anteriorly from the lobule of the ear, and posteriorly along the length of the neck down to the supraclavicular notch. Upon palpation, the mass was soft to firm, lobulated, and nodular.

Radiographic Imaging. Computed tomographic imaging of soft tissue windows reveals a well-defined predominantly cystic mass. The chest radiographs demonstrate a cannonball appearance. Multiple variable radiolucencies, seen in both lungs, are suggestive of metastasis.

Differential Diagnosis. On the basis of clinical and radiographic imaging, the differential diagnosis includes metastasis, Wegner's granulomatosis, and CXPA.

Diagnosis and Management: Fine needle aspiration was done, and was reported as CXPA. An excisional biopsy was then taken, and tissue was sent for histopathology, confirming the fine-needle aspiration diagnosis.

Clinical Implication. Understanding the underlining complications of pleomorphic adenoma makes us better equipped to render an earlier diagnosis and optimal treatment to the patient.