CT scoring system for differentiating of sinonasal inverted papilloma and squamous cell carcinoma arising from inverted papilloma.

Objective: To distinguish squamous cell carcinoma in inverted papilloma (IP-SCC) from IP, the utility of CT scoring system was investigated.

Methods: We extracted cases histopathologically diagnosed with IP and IP-SCC of the sinonasal cavity from June 2004 to May 2021. Preoperative unenhanced CT images were used to evaluate the presence or absence of bone destruction and erosion: Score 1 = positive for bone destruction and/or erosion; Score 0 = negative for bone destruction and erosion. The CT scores in 10 sites of the sinonasal cavity and their adjacent areas were calculated.

Results: Fifty-six cases of IP and 20 cases of IP-SCC were enrolled in this study. Bone destruction and/or erosion was more frequently observed in IP-SCC than in IP at the sites of the skull base (p = 0.0001), orbital wall (p < 0.0001), maxillary sinus (p < 0.0001), nasal septum (p < 0.0001), inferior nasal concha (p = 0.0046), ethmoid sinus (p < 0.0001), pterygoid process (p = 0.0031), and frontal sinus (p = 0.0009). The total CT scores at the 10 sites for diagnosing IP-SCC had sensitivity and specificity of 70% and 87.5% (AUC: 0.810, p < 0.001); furthermore, those at the eight sites excluding fontanelle and middle nasal concha improved sensitivity and specificity of 75% and 83.9% (optimal threshold of 2, AUC: 0.862, p < 0.001).

Conclusion: The CT scoring system evaluating bone destruction and erosion could accurately differentiate IP-SCC from IP.