Material and Method: The medical records of patients diagnosed as IPs at Songklanagarind Hospital between January 2004 and December 2012 were retrospectively reviewed. Demographic data, clinical presentation, type of surgical approach, complications, and recurrence status were collected.

Results: From 64 patients, 75% were male. The average age was 55 years. IPs were classified in Krouse’s classification system as followed: stage I = 6.3%, stage II = 21.9%, stage III = 70.3%, and stage IV = 1.5%. The surgical approaches were divided into endoscopic endonasal approach (EEA) 60.9%, EEA combined with external approach 35.9%, and external approach 3.2%. Complications such as synechea and maxillary sinus ostium stenosis occurred in 29.7% of patients. Thirty-seven point five percent had disease recurrence after surgery, most commonly at the frontal sinus 82.4%, and sphenoid sinus 60%.

Conclusion: EEA is an effective treatment for IPs, especially in Krouse’s classification stage I, II. The external approach combined with EEA could be useful when the tumor extends to the anterolateral wall of the maxillary sinus. Finally, the surgeon must pay particular attention to the frontal and sphenoid sinus because of the high local recurrence rate.

Keywords: Surgical outcome, Benign tumor of the nasal cavity, Inverted papillomas