Mucocele Formation after Surgical Treatment of Inverted Papilloma of the Frontal Sinus Drainage Pathway

BACKGROUND: Inverted papillomas (IP) inserted in the frontal sinus and/or recess may be treated by using an endoscopic endonasal or an external approach. There are still few data available on this uncommon localization of IPs. OBJECTIVE: To report our experience in the management of IP of the frontal drainage pathway, to describe a previously unreported specific complication of this surgery, and to discuss the optimal surgical strategy. METHODS: A retrospective study of the patients at a tertiary care center between 2004 and 2014 who were operated on for an IP with an insertion in the frontal recess and/or the frontal sinus. Clinical charts were reviewed for demographics, clinical presentation, imaging findings, surgical treatment, and outcome. RESULTS: Twenty-seven patients were included. Patients were operated on by using a purely endoscopic approach (Draf procedure; n = 14 [51.9%]) when the IP was inserted in the frontal recess and/or the frontal sinus infundibulum (with a nasoseptal-septoturbinal flap placed on the exposed bone in four patients), or by using a combined endoscopic and open approach (osteoplastic flap procedure; n = 13 [48.1%]) when the IP invaded the frontal sinus beyond the infundibulum. There were two recurrences (7.4%), with a mean follow-up of 40 months (range, 9-123 months). During follow-up, single or multiple iatrogenic frontal mucoceles were observed in 10 patients (37%), with a mean delay of 60 months (range, 27-89 months). These mucoceles occurred both after using endoscopic (n = 3) or combined (n = 7) approaches, and required a surgical treatment in eight patients. No postoperative mucocele was observed in the four patients who had had a septal flap. CONCLUSION: In our experience, an approach based on the localization of the IP insertion provided acceptable results in terms of the local control rate (92.6%). However, the significant rate of postoperative mucoceles indicated that specific strategies (such as local flaps) still need to be developed to avoid this iatrogenic complication.