Frontal mucopyocele with bone erosion in a 7-year-old child-exclusively endoscopic endonasal approach-a case report*

A mucocele is a benign lesion that predominantly affects the paranasal sinuses, with a slow growth rate and expansive pattern. When infected, it is known as mucopyocele. Presentation of a frontal mucopyocele can be found more frequently in adults. In contrast, it is rarely seen in children since pneumatization of the sinuses usually takes place after age 7. This report aims to present one case of a frontal mucopyocele as an important complication of a pansinusitis in a 7-year-old child and discuss the diagnosis, surgical approach, and differentials. Endoscopic endonasal surgery is a safe approach and must be taken into consideration in these situations.

1mg/kg for 10 days. After the treatment, it was determined that surgery should be performed.
Surgical planning was performed with a Digital Imaging and Communications in Medicine (DICOM) viewer software to analyze all images. A 3D reconstruction ( Figure 2) allowed a better understanding of the disease's behavior and, consequently, helped to define the surgical approach. This team has extensive experience with endoscopic access to the frontal sinus.
Pre-operative planning concluded that the lesion could be completely removed endoscopically. The procedure began with an endoscopic septoplasty, removing a small fragment of the superior part of the septal cartilage. After that, uncinectomy and wide antrostomies were performed, associated with a centri-petal ethmoidectomy (10) . The first fiber of the olfactory nerve

Discussion and conclusion
Although frontal mucocele is often operated in a combined approach, we were able to remove the lesion with an endoscopic endonasal technique. Transseptal access to the frontal sinus allowed for good visualization of the entire lesion. Utilization of flexible instruments and an angled (30º) endoscope was essential. Ethmoidectomy by using the Centripetal technique (10) (8,10) . Moreover, this less invasive treatment may be particularly useful in children and young adults, when the incision necessary for the external approach is not always cosmetically acceptable (11) .
Due to the distinct topography of the lesion described in this case, pre-surgical planning was of great importance. Using a DICOM viewer software to analyze the images, it was possible to accomplish a 3D reconstruction. 3D images allowed for a better understanding of the disease's behavior, which was of great value in deciding the approach to be used.
Although frontal sinusitis in children is unusual, it is a disease that should be considered and may cause severe complications.
Surgical planning is facilitated when a thorough tomographic study is first done using digital DICOM viewer tools. 3D reconstruction can give more confidence to the surgeon performing the intervention. Additionally, in cases of greater complexity, it is fundamental to foresee possible difficulties that shall be faced during the operation, especially the ones regarding material and instruments that will be used. Even when proper measures are taken, new obstacles may arise. Thus, a deep knowledge of anatomy, alongside high-level surgical training, is needed to The open technique is a procedure that and can be safely performed with good results. However, the endoscopic endonasal approach is a less invasive option, with lower morbidity and similar recurrence rate (close to 0%) (11)(12)(13)(14). In consideration of a 7-year-old patient, the endoscopic endonasal approach was a good option since it allowed the removal of the disease without aesthetic damage, presented low morbidity and good recovery in the post-operative period. The case was exhaustively studied and after thorough analysis of the images (CT scan and MRI), we have concluded that it was possible and worth doing the surgery by endonasal access, even with predicted difficulties, which did occur. We could manage them, however, with the use of angled endoscopes and instruments; some of them needed to be reshaped during the surgery. This procedure was able to successfully provide removal of the mucocele. The postoperative had no complications, with no evidence of recurrence two years after the surgery. The endoscopy examination presents no signs of disease and the patient remains asymptomatic, normally developing cranio-facial structures, confirming that the procedure accomplished its goals. With the endoscopic approach it might have been more difficult to manipulate certain areas of the frontal sinus, especially in higher and lateral areas. However, this case shows that even those locations can be accessed and present excellent outcomes with low morbidity and great disease control, making it a valuable option that must be considered in similar conditions.