Snapshot A 58-year-old woman presents to the physician with complaint of a painless lump on the left side of her face. She describes that she first noticed the lump more than 5 years ago, when it was small in size. However, it has progressively grown with time to the present size. Her husband notes that the patient's speech has changed slightly in the past year. Physical exam is notable for facial asymmetry and a firm, nontender mass on the left side of the face below the lower border of the mandible, as seen in the image. There was no palpable lymphadenopathy in her neck. Introduction Overview pleomorphic adenomas are benign salivary gland tumors predominantly affect the superficial lobe of the parotid gland Epidemiology Incidence most common tumor affecting the salivary glands, accounting for 70% of parotid tumors and 50% of salivary tumors Demographics most commonly affects women between 30-50 years of age Risk factors radiation exposure ETIOLOGY Pathophysiology tumor has both epithelial and connective tissue origin may undergo malignant transformation tumor lacks a true capsule and may have microscopic extensions results in a high risk of recurrence in cases treated with surgical resections performed with inadequate surgical margins Presentation Symptoms solitary, mobile slow-growing painless mass may be present for many years dysphagia hoarseness difficulty chewing facial weakness if facial nerve is affected Physical exam solitary, mobile, nontender mass facial asymmetry or droop may be present Imaging CT or MRI findings smoothly marginated or lobulated soft tissue globular mass necrosis may be seen in larger masses few foci of calcification may be seen Ultrasound findings hypoechoic mass can allow for ultrasound-guided fine needle aspiration or biopsy Studies Tissue sampling fine needle aspiration determine whether tumor is malignant or benign core needle biopsy allows for histological typing of the tumor Differential Other tumors of the salivary and parotid glands (i.e., Warthin tumor, metastasis to the parotid gland, facial nerve schwannoma, mucoepidermoid, and adenoid cystic carcinoma) key distinguishing factor histopathology will be unique to the tumor Treatment Surgical superficial or total parotidectomy indication pleomorphic adenoma of the parotid gland tumor excision with preservation of adjacent nerve indication pleomorphic adenoma of the submandibular and minor salivary glands Complications Recurrence of tumor after surgical resection associated factors incomplete capsule extension of tumor nodules beyond the capsule tumor rupture during surgical resection Malignant transformation incidence 2-7% of cases associated factors multiple tumor recurrences deep lobe tumors male gender increased age Prognosis Excellent after surgical resection with adequate surgical margins