DETECTION OF PERINEURAL SPREAD OF PALATAL ADENOID CYSTIC CARCINOMA BY CT

Abstract

<h3>Background</h3> A large fraction of adenoid cystic carcinoma (ACC) tumors progresses to perineural spread (PNS), with correspondingly low long-term survival rates, and ACC is often not diagnosed in early stages because the primary tumor site is hard to detect. <h3>Objective(s)</h3> This study aimed to improve detection of ACC by better understanding the imaging features of PNS. Specific aims included (1) determining whether ACC could be effectively diagnosed by CT alone using a CT bone window to examine osseous changes; (2) determining the accuracy of CT-based diagnosis; and (3) exploring the relationship between the presenting clinical features and perineural spread. <h3>Study Design</h3> A retrospective medical records search was performed from 2000 to 2017 to identify patients with a diagnosis of ACC, clinical history, and pretreatment imaging with CT and/or MRI. Descriptive statistics, as well as sensitivity and specificity data, were compared using likelihood ratio test. <h3>Results</h3> Forty-four patients (median age 51 years; range 20–87 years) met the inclusion and exclusion criteria. The most common symptoms, not mutually exclusive, included pain (41%), mass (41%), paresthesia or numbness (39%), and sinonasal congestion (21%). Most (46%) patients presented to their dentist for initial evaluation, and 55% were evaluated by a dentist at some point before diagnosis. The most common initial impressions were infection (50%) and/or dental disease (32%). Average time to histologic diagnosis from initial symptoms was 18 months. PNS was identified in 82% of all patients. Significantly, findings of erosion and/or enlargement of any foramina, fossae, or canals noted via bone-windowed CT were 97% sensitive and 100% specific for PNS. PNS was statistically associated with paresthesia (<i>P</i> = .003; specificity 100%; sensitivity 47%) but not with tumor size (<i>P</i> = .096). <h3>Discussion/Conclusions</h3> Palatal ACC PNS can be reliably diagnosed via bone-windowed CT. Dentists are often the first care providers and should be aware that patients presenting with numbness should be evaluated for PNS.