What causes pleomorphic adenoma of the parotid gland?

Pleomorphic adenoma of the parotid gland is most commonly seen in middle-aged individuals. It typically presents with no obvious subjective symptoms and grows slowly, with a disease course lasting several years—or even decades—making it easy for patients to overlook. Although pleomorphic adenoma is benign, it carries a risk of malignant transformation, estimated at approximately 3%–5%. The longer the duration of the disease, the higher the risk of malignancy; after 15 years, the malignant transformation rate rises to 9.5%. So, what causes pleomorphic adenoma of the parotid gland? The following section addresses this question.

What Causes Pleomorphic Adenoma of the Parotid Gland?

In general, the exact etiology of pleomorphic adenoma remains unclear. Most experts believe its development is associated with external stimuli during embryonic growth and development. Pleomorphic adenoma predominantly affects young adults aged 20–30 years and typically arises in the region surrounding the parotid gland. After onset, patients usually experience no prominent symptoms or discomfort; the only noticeable sign may be a painless mass in the parotid region. Growth is extremely slow, often spanning over a decade, eventually leading to facial asymmetry and impairing normal daily life. Additionally, pleomorphic adenoma is the most common benign tumor of the parotid gland; it is termed “pleomorphic” because its tissue contains structures derived from multiple cell types—including glandular epithelial cells, ductal cells, and mucous-producing cells.

Knowledge Expansion: Symptoms of Pleomorphic Adenoma of the Parotid Gland

1. Pleomorphic adenoma of the parotid gland is a common benign tumor arising in the parotid gland. Clinically, it manifests as a firm, painless mass located below the earlobe or anterior to the tragus. Such masses are asymptomatic and grow slowly; in some patients, the tumor remains unchanged for years. However, pleomorphic adenoma carries an inherent potential for malignant transformation.

2. During long-term progression, sudden enlargement of the tumor, facial nerve palsy (facial paralysis), or localized pain may occur—clinical signs strongly suggestive of malignant transformation. Moreover, recurrent tumors following multiple surgeries also carry an increased risk of malignancy. Therefore, once diagnosed, surgical excision is recommended for all pleomorphic adenomas of the parotid gland, regardless of size.

The above outlines the etiology of pleomorphic adenoma of the parotid gland. We hope this information is helpful to you.