Maxillary Sinus Mucocele following Zygomaticomaxillary Complex Fracture Repair.

Maxillary sinus cysts typically occur as postoperative maxillary cysts arising years after sinonasal surgery. In contrast, trauma-related cysts are uncommon, and cases specifically following zygomaticomaxillary complex fracture repair are exceedingly rare. We report a maxillary sinus cyst that developed 28 years after open reduction and internal fixation of a zygomaticomaxillary complex fracture. At the initial injury, the orbital floor fracture remained untreated, and the posterior maxillary wall was displaced anteriorly. These structures likely contacted each other and formed a bony partition, creating a closed intramaxillary cavity adjacent to the orbit and lined with mucosa, in which a cyst gradually developed. The patient presented with worsening left cheek pain. Imaging revealed a cystic lesion in the left maxillary sinus abutting the orbital contents. Although plate infection was initially suspected, symptoms persisted after plate removal and partial curettage. On referral, no signs of local infection were present. Computed tomography (CT) demonstrated the bony partition and a posteriorly expanding cyst with bone erosion. Because the cyst occupied a closed compartment, establishing drainage was essential. A combined approach with otolaryngologists was performed. Through a subciliary incision with endoscopic endonasal assistance, the bony septum was removed, creating communication with the native maxillary sinus. The orbital floor was reconstructed using an iliac inner table graft. Postoperatively, pain resolved, and computed tomography confirmed patency of the drainage route. No recurrence was observed at 1 year. This case illustrates that long-standing anatomical deformities after facial trauma may predispose to delayed cyst formation and require long-term attention.