It is also known as "Mixed tumor, salivary gland type", which refers to its dual origin from epithelial and myoepithelial elements as opposed to its pleomorphic appearance.

Although it is "benign", the tumor is aneuploid, it can recur after resection, it invades normal adjacent tissue, and distant metastases have been reported after long (+10 years) time intervals.

The majority of the lesion are found in patients in the fourth to sixth decades with an average age of occurrences of about 43 years, but these are relatively common in young adults and have been known to occur in children.

Classically it is biphasic and is characterized by an admixture of polygonal epithelial and spindle-shaped myoepithelial elements in a variable background stroma that may be mucoid, myxoid, cartilaginous or hyaline.

Epithelial elements may be arranged in duct-like structures, sheets, clumps and/or interlacing strands and consist of polygonal, spindle or stellate-shaped cells (hence pleiomorphism).

Fine needle aspiration biopsy (FNA), operated in experienced hands, can determine whether the tumor is malignant in nature with sensitivity around 90%.

CT allows direct, bilateral visualization of the salivary gland tumor and provides information about overall dimension and tissue invasion.

More detailed surgical technique and the support for additional adjuvant radiotherapy depends on whether the tumor is malignant or benign.

[9][10][11] Thus, detection of early stages of a tumor of the parotid gland is extremely important in terms of prognosis after surgery.

Enucleation of the tumor (i.e. intracapsular dissection), a procedure that was common in the early 20th century, is nowadays obsolete due to very high incidence of recurrence.

[9] After the time of enucleations, pleomorphic adenomas of parotid gland were recommended to be routinely treated with superficial or total parotidectomy.

[9][16] Currently, the choice of surgical approach for parotid pleomorphic adenoma is mainly based on the size, location, and mobility of the tumor.