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Neuroradiology Case of the Week

Case 185

Scott Cassar, MD, Farhad Farzanegan, MD,
and Per-Lennart Westesson, MD, PhD, DDS

Clinical Presentation: A 55-year old male with a history of Stage I Hodgkin’s disease status post chemotherapy and radiation therapy.

Radiological Findings: There is a well-defined isodense area anterior to the left parotid gland and anterolateral to the left masseter muscle.

Diagnosis: Accessory parotid gland

Discussion: Accessory parotid glands are true parotid tissue lying distinctly separate from the parotid gland proper. They lie along and drain into Stensen's duct. Twenty-one per cent of the population has clearly detached accessory glands at variable distances from the main gland. There are no appreciable histopathologic differences between the accessory gland and the main gland in the same facial half. Aging changes, such as decreased glandular elements, increased fat, and increased fibrous connective tissue, are not more extensive in the accessory gland than in the main gland. Because of the histologic similarity, pathology of the main gland can also involve the accessory parotid gland. Failure to remove a distantly separated accessory gland during parotidectomy could be a cause of tumor recurrence. Between 1% and 7% of all parotid neoplasms arise from the accessory glands, and 50% of these are histologically malignant.

References:

1. Batsakis JG. Accessory parotid gland. Ann Otol Rhinol Laryngol. 1988 Jul-Aug;97(4 Pt 1):434-5. [Medline]
2. Frommer J. The human accessory parotid gland: its incidence, nature, and significance. Oral Surg Oral Med Oral Pathol. 1977 May;43(5):671-6. [Medline]
3. Nemecek JR. Marzek PA. Young VL. Diagnosis and treatment of accessory parotid gland masses. Ann Plast Surg. 1994 Jul;33(1):75-9. [Medline]