Objective: Morphologic criteria for the diagnosis of primary and recurrent inverted papilloma as revealed on CT were evaluated in a large series.
Materials and methods: Findings of 121 CT examinations that had been performed in 32 patients with histologically proven inverted papilloma were retrospectively analyzed using the following morphologic criteria: localization, size, surface configuration, and bony changes.
Results: Unilateral tumor localization involving the lateral nasal wall and the middle meatus was the feature that best correlated with the finding of primary inverted papilloma. A lobulated surface pattern was another typical sign, which was revealed on 19 of the 29 CT scans of patients with primary inverted papilloma. Although tumor localization and the finding of a newly grown soft-tissue mass were less reliable criteria to differentiate between recurrent inverted papilloma and postoperative complications or concomitant inflammatory disease, a lobulated surface pattern was seen on 26 of the 28 CT scans of patients with tumor recurrence but on only three of the 64 follow-up CT scans of patients without recurrent inverted papilloma.
Conclusion: A unilateral mass within the nasal cavity or paranasal sinuses with a surface configuration that appears lobulated on CT is, to our knowledge, a new sign that strongly suggests inverted papilloma as a primary diagnosis and also suggests inverted papilloma in patients with tumor recurrence.