There are two types of anterior gland extensions: 

• facial process: attached to the main gland
•  detached glandular mass / accessory parotid gland: mean distance of separation from the gland of 6 mm

Accessory parotid glands are seen in 20% of the population. It usually occurs in a typical location i.e. overlying the masseter muscle and anterior to the parent gland. It lies superficial to the Stensen's duct and drains via an accessory duct into it. They have an independent blood supply from the transverse facial artery. These glands are usually small in size, may be multiple. Tumors of accessory glands are rare.