• An accessory parotid gland is defined as "a collection of salivary tissue separate from the main parotid gland" but still connected by the duct (Ahn 2017)
• A facial process is defined as "the parotid lobe protruding anteriorly along the course of the parotid duct while maintaining continuity with the main gland" (Ahn 2017)
• Reported incidence of accessory parotid gland is 21-69% (Ahn 2017)
• An accessory parotid gland typically lies anteriorly overlying the masseter (Ugur 2024)
• Typical size is from a pea to kidney bean (Ahn 2017)
• Mean distance from accessory parotid gland to main parotid gland has been reported to be 10.5 mm with range of 1-37 mm (Ahn 2017)
• Lesions of the accessory parotid gland represent 1-8% of all parotid gland lesions (Hasegawa 2021)
• Histologically, the accessory parotid gland has serous and mucous acini (Ugur 2024)

Radiologic Findings

• Imaging will show tissue with densities and signals equal to those of normal salivary tissue
• Ultrasonography may be used as the first-line imaging modality due to accessibility, non-invasive and non-ionizing nature, and low cost (Ugur 2024)

References

Ahn D, Yeo CK, Han SY, Kim JK. The accessory parotid gland and facial process of the parotid gland on computed tomography. PLoS One. 2017;12(9):e0184633. Published 2017 Sep 15. doi:10.1371/journal.pone.0184633

Hasegawa K, Sukegawa S, Ono S, Ando M, Shibata A, Sukegawa-Takahashi Y, Fujimura A, Matsuyama T, Ibaragi S, Nagatsuka H, Mizobuchi K, Sasaki A, Furuki Y. Endoscopic-assisted resection of pleomorphic adenoma in the accessory parotid gland. J Med Invest. 2021;68(3.4):376-380. doi: 10.2152/jmi.68.376. PMID: 34759162.

Uğur TA, Tercanlı H. Evaluation of the anterior processes of the parotid gland: an ultrasonographic study. Surg Radiol Anat. 2024 May 4. doi: 10.1007/s00276-024-03369-y. Epub ahead of print. PMID: 38703221.