Numerous types of malignant parotid tumors are seen, the most common being adenoid cystic carcinoma, mucoepidermoid carcinoma, squamous cell carcinoma, and acinic cell carcinoma. A growing mass is the main symptom, sometimes accompanied by facial nerve palsy and associated pain, but in the majority of cases, an asymptomatic course is observed until the tumor reaches an advanced stage. The initial diagnosis is made through a physical examination, whereas imaging studies, and a histopathological exam (either preoperative or postoperative) are recommended for confirming the exact etiology.
Tumors of the parotid gland constitute about 80% of all salivary gland tumors, which are rarely encountered in clinical practice  . Approximately 20% of all tumors are malignant in nature, with numerous subtypes are described in the literature  . Adenoid cyst carcinoma, squamous cell carcinoma, mucoepidermoid carcinoma, acinic cell carcinoma, as well as lymphomas and mixed tumors are the main types of primary malignant parotid tumors   . In addition, recurrences of previously resected tumors constitute a small, but significant proportion of malignant parotid tumors . These malignancies are encountered at the end of the sixth and the beginning of the seventh decade (mean onset around 60 years of age), with no gender predilection   . Several risk factors have been attributed to the pathogenesis, such as cigarette smoking and alcohol, but the exposure to high doses of ionizing radiation is the only definite risk factor . Malignant parotid tumors are generally described as slow-growing lesions, (which may result in an insidious clinical course) , and a small, well-defined, and mobile lump can be identified as the only finding . In more aggressive forms, the mass grows rapidly and produces symptoms such as pain, facial paralysis (due to facial nerve palsy), and proximal lymphadenopathy   . Because metastatic spread of tumors, particularly into the lungs , are a known complication of malignant parotid tumors, their early recognition is vital.
The physician plays a crucial role in identifying malignant parotid tumors in its early stages, which could lead to a very good prognosis (5-year survival rates of tumors in stages I and II are 96% and 77%, respectively) . For this reason, a thorough patient history that evaluates the presence of associated complaints and their duration, together with a meticulous physical exam that includes palpation of the parotid glands, are essential steps for raising clinical suspicion. After a nondisclosed mass is observed in the parotid gland, imaging studies should be ordered as soon as possible. Ultrasonography (US) is a reliable first-line method that can detect a mass and determine its basic characteristics, particularly if the mass is located in the superior lobe of the parotid gland   . If inconclusive findings are obtained during the US, computed tomography (CT) or magnetic resonance imaging (MRI) might be employed for a better delineation of the lesion   . The use of a preoperative biopsy is still a matter of debate when it comes to malignant parotid tumors. Some authors advocate the use of a fine-needle aspiration biopsy (FNAB), or even an open biopsy, but both procedures carry a high risk of tumor seeding into the adjacent tissues   . Thus, a post-operative examination of the tumor through a histopathological evaluation is considered to be a definite diagnostic measure .