Endoscopic Marsupialization of Frontal Sinus Cholesterol Granuloma via a Draf IIb Approach: A Case Report

Frontal sinus cholesterol granuloma (CG) is a rare, non-neoplastic inflammatory lesion that has traditionally been managed by open surgical approaches. A 48-year-old man presented with a one-year history of localized swelling of the left forehead. Computed tomography demonstrated two expansile lesions in the left frontal sinus. The larger lateral lesion was surrounded by diffusely thinned bone, with focal defects in the anterior frontal sinus wall and orbital roof. It protruded through these defects into the orbit and displaced the orbital contents inferiorly. Magnetic resonance imaging showed predominantly high signal intensity on both T1- and T2-weighted images with minimal contrast enhancement, leading to a preoperative suspicion of CG; the smaller medial lesion was considered a mucocele. Endoscopic sinus surgery was performed. The medial lesion and lateral CG cavity were marsupialized, and a left Draf IIb frontal sinusotomy provided adequate access to the lateral frontal sinus. The CG cavity contained yellow-brown muddy fluid admixed with abundant yellow granular material. After irrigation and removal of the contents, complete excision of the cyst wall was not attempted. Exposed bone was covered with a superior lateral anterior pedicle flap and a middle turbinate-based mucosal flap, and a Penrose drain was positioned to maintain patency and permit postoperative irrigation. Histopathological examination confirmed CG. The drain was removed three months after surgery. The frontal sinusotomy and marsupialized opening remained patent, with no evidence of recurrence during 21 months of follow-up. Endoscopic marsupialization is a useful, minimally invasive treatment option for frontal sinus CG when adequate access can be achieved.