Surgeon-performed ultrasound for the assessment of parotid masses☆
Introduction
Imaging studies play a key role in the evaluation of parotid gland masses. Compared to other imaging options of computed tomography (CT) and magnetic resonance imaging (MRI), ultrasound (US) is inexpensive, less time-consuming, and lacks the problems of radiation, claustrophobia, and metal incompatibility. US can be conveniently used in real-time in clinic during a patient encounter, intraoperatively by surgeons, and can guide the performance of fine needle aspiration (FNA) biopsies of parotid masses. While the use of surgeon-performed ultrasound (SP-US) for thyroid lesions is increasingly reported in the medical literature [[1], [2]], citations on parotid gland US assessments performed specifically by surgeons are scarce.
It is unclear how reliably US can differentiate between benign and malignant parotid lesions, whether it provides sufficient information for surgical planning, and whether surgeons can demonstrate similar accuracy statistics. A variety of sonographic features such as echogenicity, heterogeneity and border characteristics have been described that correspond with the more common pathologies of pleomorphic adenoma, Warthin tumor and malignancy [3]. Some studies have also found sonographic analysis to accurately differentiate benign and malignant parotid tumors [[4], [5]]. US has been advocated as the sole imaging modality before surgery in FNA-confirmed benign lesions of the superficial parotid lobe [6]. However, the deep parotid lobe and particularly the parapharyngeal space are difficult to assess with US because of the acoustic shadow of the mandible [7]. Other studies have found US to be inferior to MRI in the evaluation of deep lobe and malignant tumors [8], and insufficient without FNA in reliably distinguishing benign and malignant tumors [[9], [10], [11]]. One meta-analysis compared US, CT and MRI with histologic diagnosis and found US to have inferior sensitivity and superior specificity [12]. Moreover, there is a paucity of studies on imaging characteristics showing predictive ability for locating parotid tumors in relation to the facial nerve (FN).
This study has three aims related to SP-US of parotid masses: 1) assess the ability of SP-US to predict parotid mass benignity or malignancy and positive margins for benign or malignant tumors; 2) in a possible novel effort, find location measurements to help predict the relation of the tumor to the FN (superficial or deep); 3) in cytologically benign parotid tumors, assess the possible influence of additional pre-parotidectomy CT or MRI on management decisions.
Section snippets
Materials and methods
After approval by the institutional review board at the University of California, San Francisco (UCSF), a retrospective review was performed of consecutive patients with a parotid mass who had a preoperative office-based SP-US and underwent parotidectomy between 2012 and 2017 (152 cases) by a single surgeon, WRR. Inclusion criteria for this study were: [1] a patient with a previously untreated parotid mass; [2] an evaluable preoperative clinic-based SP-US; and [3] a parotidectomy performed at
Results
Between May 2012 and June 2017, a total of 152 consecutive patients underwent parotidectomy. Of these, 119 patients had undergone preoperative in-office SP-US. Eighty-nine patients had full interpretable archived SP-US records available for full analysis. After exclusions for multifocal recurrent pleomorphic adenoma, chronic sialadenitis, or elective parotidectomy for occult malignancy, a total of 69 patients met all eligibility criteria (Table 1). One patient had bilateral parotidectomies;
Discussion and conclusions
This study analyzes the ability of SP-US to predict parotid mass benignity or malignancy, positive margins, and the location of the tumor relative to the facial nerve, as well as its ability to be used as the sole image modality for benign parotid masses. Preoperative SP-US features significantly associated with malignancy and positive margins included extraparenchymal extension, irregular borders, hypervascularity, infiltration and lack of deep enhancement, which are consistent with existing
Source of financial support or funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflict of interest statement
William R. Ryan, MD is on the Scientific Advisory Boards for Olympus and Medtronic and is a consultant for Ziteo.
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Cited by (12)
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2023, Indian Journal of Otolaryngology and Head and Neck SurgeryEpithelial malignant tumors of the parotid salivary glands in children and adolescents
2023, Pediatric Hematology/Oncology and ImmunopathologyPoint-of-care ultrasound scan as the primary modality for evaluating parotid tumors
2022, Laryngoscope Investigative OtolaryngologyApplication value of shear wave elastography in salivary gland tumors
2021, Oral Radiology
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Abstract presented as an oral presentation at the 2017 AAO-HNSF Annual Meeting in Chicago, IL, USA on September 10, 2017.