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E1192. Navigating the Parotid Glands: Anatomy, Imaging Work-up, and Next Steps
Authors
  1. Ryan McGeary; Mayo Clinic
  2. Amit Desai; Mayo Clinic
  3. Alok Bhatt; Mayo Clinic
Background
The parotid gland represents the largest of the salivary glands of the head and neck making for convenient clinical evaluation and typically an easy target for percutaneous procedures. Though this superficial structure may seem straightforward, the work-up of a parotid lesion has proven to be more challenging given the highly variable appearance of both benign and malignant parotid lesions. In this article, the current understanding of both malignant and benign imaging features of parotid lesions are reviewed with attention to which lesions necessitate biopsy. Additionally, current biopsy methods will be reviewed based on lesion accessibility/location in hopes to provide the radiologist with a more complete understanding of the work-up of this gland.

Educational Goals / Teaching Points
The radiologic approach to the parotid gland will first begin with a brief guide to relevant anatomy covering vascular, lymphatic, fascial, and nervous components of the parotid gland, focusing on clinical pertinence. With this foundation in place, review of parotid lesion imaging characteristics will be presented as they relate to malignant potential based on the current literature. When and when not to biopsy a given parotid lesion becomes the question. These imaging characteristics will then be broken down into either a biopsy “do” or a biopsy “don’t.” Subsequent sampling of a superficial parotid lesion may be amenable to ultrasound-guided core needle biopsy, but deeper lesions may require a more complex approach with requirement of cross-sectional guided imaging; these approaches will be discussed.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
A lesion in the parotid gland may have imaging characteristics that favor a benign or malignant entity. For instance, a well circumscribed “pear shaped” lesion in the deep parotid lobe with very high T2 signal is often the textbook appearance of a benign pleomorphic adenoma. These “typical” presentations are convenient to deal with, but what if the margins were ill-defined? What if the signal characteristics depart from what is expected? These possibilities are explored in this exhibit with the goal providing a step-by-step approach to these “atypical” cases. Beyond concerning imaging features that necessitate biopsy, this exhibit will also inform the radiologist as to what type of biopsy may be needed and how it is generally performed.

Conclusion
The overall aim of this educational exhibit is to provide the radiologist with the most up to date understanding of the parotid gland and associated lesions from an imaging perspective. This review of the parotid gland from anatomy, imaging features of lesions, as well as biopsy techniques should serve as a guide for the radiologist in order to properly guide management in patients with parotid pathology.