High CT attenuation values relative to the brainstem may predict squamous cell carcinoma arising from inverted papilloma

Background: A diagnostic indicator for differentiating squamous cell carcinomas (SCCs) from inverted papillomas (IPs) has not been established. Objectives: This study aimed to evaluate whether CT attenuation values relative to those of the brainstem (relative CT number) could be useful in differentiating IPs from SCCs. Material and Methods: Consecutive patients who were pathologically diagnosed with IP or SCC between 2007 and 2017 were retrospectively identified. Relative CT numbers were compared between the two patient groups. The factors with predictive power for differentiating IPs from SCCs were identified by univariate and multivariate logistic regression analyses. Results: Fifty-four sinonasal tumour cases were finally analysed (IP, 25 cases; SCC, 29 cases). Relative CT numbers were significantly higher in SCC than in IP (p <.001). The univariate logistic regression analysis showed BMI, relative CT number, and disease duration to have predictive value for differentiating IPs from SCCs. In the multivariate logistic regression analysis, only the relative CT number had predictive value for distinguishing IP from SCC (odds ratio, 1.97), with a relative CT number of ≥1.4 being significantly associated with SCC. Conclusions: High relative CT numbers could potentially be used to identify SCCs, and their measurement could provide a basis for differentiating IPs from SCCs.