Diagnostic Workup
After initial prescreening during the telemedicine encounter, patients with signs or symptoms of a salivary gland mass should undergo diagnostic imaging. All patients must be screened for symptoms of COVID-19 or risk factors for exposure prior to their visit to the radiology department. Imaging studies of the patients with the symptoms concerning for COVID-19 should be cancelled and delayed until the diagnosis is confirmed and they recover from their illness, or COVID-19 is ruled out with negative test results unless this delay has a high probability of significant negative outcome for the patient.7 The most up-to-date institutional guidelines should be used to determine who needs COVID-19 testing. If possible, patients must undergo imaging at the sites with less foot traffic and with fewer critically ill patients to prevent secondary exposure to COVID-19.
The goal of radiographic evaluation is to assist in the triage of patients with a suspected salivary gland mass and to determine if the patient has a lesion requiring a tissue diagnosis for treatment recommendations. The most readily available imaging studies must be utilized with the preference given to ultrasonographic evaluation due to ease of performance and the ability to immediately obtain a fine-needle aspiration biopsy (FNAB) of identified lesions for cytopathologic analysis (Table 1). Since several benign and malignant salivary gland lesions can present with minor or predominant cystic component, and one third of cystic salivary gland lesions are neoplastic,8 presence of a cystic component on ultrasonography should not serve as a determining factor in the decision to proceed with FNAB. Salivary gland ultrasound can also aid in the diagnosis of sialolithiasis or other inflammatory salivary gland conditions, and guide further treatment recommendations.9,10 If FNAB cannot be done, consideration should be given to contrast-enhanced magnetic resonance imaging (MRI) instead of the ultrasound to confirm presence of a salivary gland mass and to look for radiographic features of common benign or malignant salivary gland tumors.
Clinical situations of radiographically diagnosed salivary gland masses, especially deep parotid lobe masses not amenable to FNAB must be approached on a case-by-case basis with diagnostic options of either computed tomography (CT) guided biopsy or surgical resection. The final diagnostic choice will depend on the availability of the hospital’s interventional radiology department and COVID-19 burden. For patients with minor salivary gland tumors of the oral cavity, sinonasal region and pharynx diagnosed based on the office-based biopsy, appropriate cross-sectional imaging of the head and neck should be performed upfront to determine the extent of the lesion and the treatment plan.
Telemedicine visits can be used to determine the best location for salivary gland imaging. Good knowledge of local private imaging facilities willing to perform salivary gland ultrasound, FNAB or other head and neck imaging when the hospitals with high volume of COVID-19 patients postpone it will help determine best options for radiology referrals. Fortunately, evaluation of major salivary gland neoplasms can be done without oral or nasal examination, and some otolaryngology physicians have the capabilities to perform an ultrasound and an FNAB in the office. After completion of salivary gland ultrasound and FNAB, MRI with contrast must be reserved for preoperative planning in patients with time-sensitive diagnosis such as salivary gland malignancy and can be ordered on the basis of the US and the FNAB results if indicated. Imaging of sialolithiasis and other inflammatory salivary gland conditions (CT or sialo-MRI) should be postponed in the majority of patients. However, in rare situations such imaging might become unavoidable (Figure 1).
Ultrasound characteristics alone cannot distinguish benign from malignant salivary gland masses, and must be considered in conjunction with the FNAB results.11,12 FNAB results can be stratified by the Milan System for Reporting Salivary Gland Cytology (MSRSGC)13-14 to render treatment recommendations. Repeat FNAB must be considered if the initial FNAB results are interpreted as “non-diagnostic” (Table 2). Personal protective equipment (PPE) should be used appropriately while performing FNAB procedures and handling specimens according to the College of American Pathologist guidelines.15 Only essential members of the health care team should be present during the FNAB procedure to reduce exposure as expelling aspirates may generate droplets or aerosols. In addition, agitating air-dried smears should be minimized.