We read with great interest the letter by Karligkiotis et al. which characterizes techniques for avoiding mucocele formation following skull base reconstruction with pedicled nasoseptal flaps. This letter was in response to our previously published case report describing the development of a sphenoid sinus mucocele that formed under a septal flap following endoscopic endonasal pituitary surgery . Karligkiotis et al. recommended aggressive removal of the sphenoid mucosa prior to flap placement. They also recommended marking the mucosal surface of the flap prior to harvesting in order to maintain flap orientation and prevent incorrect placement of the mucosal surface against the skull base defect. They suggested that these and other techniques could reduce mucocele formation to 0%.

We agree with Karligkiotis et al. that incomplete removal of underlying mucosa may be a potential factor in mucocele formation after septal flap reconstruction , and we do routinely remove underlying mucosa before placement of the flap. However, the possible development of mucoceles despite meticulous surgical technique should not be discounted. The nasoseptal flap for skull base reconstruction is a fairly new technique with most series reporting good results and rare mucocele formation in relatively short term follow-up . We suspect that with longer-term follow-up, the incidence of mucocele formation may actually be higher. As a related example, frontal sinus obliteration was initially thought to have a low rate of mucocele formation, only to find many years later that delayed onset mucoceles could occur with regularity in long-term follow-up . Some of these frontal mucocele complications were likely related to incomplete removal of frontal sinus mucosa at the original procedure, but one would also suspect that a portion of the delayed mucoceles occurred despite complete mucosal exenteration of the frontal sinus.

Karligkiotis et al. also proposed that mucocele formation may be the result of placement of the mucosal surface against the defect and surrounding bone rather than the mucoperiosteal/mucoperichondrial surface. Whether this could actually result in mucocele formation is debatable. We feel that placement of the mucosal surface of the flap against the skull base defect would be more likely to result in flap non-take or failure than subsequent mucocele formation, since the secretory nature of the mucosal surface would likely prevent the flap from adhering to the skull base defect. Karligkiotis also suggested that marking the flap prior to harvesting may help to prevent flap misorientation. We agree that marking the mucosal surface of grafts can be important, particularly in the case of free mucosal grafts. Since the nasoseptal flap is pedicled, we feel that adequate orientation can usually be maintained by tracing the flap to its pedicle and ensuring that the pedicle is not twisted. Once the pedicle has been visualized and secured, misorientation of the flap can usually be prevented. In the case of a flap that is twisted on itself, there is perhaps a very slight possibility that a mucocele may form along the pedicle (not under the flap), but such an occurrence could be expected to be very rare.

We appreciate the comments of Karligkiotis et al, and agree that meticulous surgical technique can minimize the risk of delayed mucocele formation, but reducing the incidence of mucocele formation to zero may be difficult to achieve even under the best surgical conditions.