This Croatian study aimed to look at risk factors associated with malignant transformation and recurrence in 91 cases in a single institution over a 20-year period. There were 66 men and 25 women included in the study.
The authors reported a rate of recurrence of 18.7% and malignancies occurred in 13% of patients. Of the 66 male patients, 19.7% had recurrence and 15% had malignant transformations, with nine occurring as synchronous to inverted papilloma and one occurring nine years after the initial surgery.
All of the malignancies were diagnosed as squamous cell carcinomas at the initial surgery, but the recurrent case was an adenocarcinoma. Of the 25 female patients, 16% had recurrence and 8% had malignant transformations. Both of these malignancies occurred synchronously to the inverted papilloma. The mean time to first recurrence was two years. The odds ratio for men to develop carcinoma was 2.06 (95% CI 0.004-10.1) and 1.44 (95% CI 0.4-5). There were no significant differences regarding patients’ age and sex and malignant transformation or recurrence. This study provides a useful summary of a large case series of patients with inverted papilloma and suggests that the risk of developing malignancy after an initial benign finding is low.
