Post-traumatic ethmoid mucocele following penetrating craniofacial injury.

A 52-year-old woman presented with an 8-month history of progressive right-sided facial pain and headache. Her medical history was significant for a gunshot wound to the face approximately 10 years earlier. The bullet had entered her face at the left glabellar region and had become lodged in the fight posterior orbit. Soon after the injury, the patient underwent enucleation of the globe and placement of an orbital prosthesis. The bullet was not removed during her primary surgery.

Our workup, which included computed tomography (CT) of the paranasal sinuses and orbit, identified old comminuted fractures of the bilateral nasal bones and the anterior aspect of the right medial orbital wall. CT also detected an expansile lesion that involved the fight frontal and fight anterior ethmoid sinuses; local remodeling of the bony sinus walls was also evident (figure). Magnetic resonance imaging (MRI) was initially recommended but not performed because of the presence of the retained foreign body in the orbit (figure, B). The patient was diagnosed with a presumptive traumatic mucocele, and she underwent diagnostic endoscopy and surgical decompression of a right frontoethmoid mucocele. She recovered uneventfully.

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Mucoceles are the most common expanding lesions involving the paranasal sinuses. They develop secondary to several etiologies, including (1) an obstructed sinus ostium, (2) within a compartment of a septated sinus, or (3) an entrapment of mucosa within a sinus fracture line, usually the frontal sinus. Structurally, mucoceles resemble simple cysts. They are made up of a mucoid core that is surrounded by an epithelial lining. The cyst wall constitutes the sinus mucosa. As the sinus cavity expands, the bony sinus walls remodel to accommodate the enlarging cyst.

The most common site of mucocele development is the frontoethmoid suture region. In rare instances, mucoceles involving the maxillary sinus have been reported. Inflammation clinically signifies a mucopyocele. On CT, a mucocele usually appears as an expanded sinus cavity filled with homogeneous material. One or more sinus walls may be remodeled and may appear as normal, thin, or eroded bone. In the case of bone erosion, only the sinus mucosa and the periosteum of the bone cover the mucoid fluid.

Clinically, patients may present with severe symptoms, including proptosis, meningitis, osteitis of the frontal bones, and orbital complications secondary to expansion of an infected mucopyocele into the orbit. The initial workup and preoperative planning are guided by CT in the axial and coronal planes and by MRI when the latter is not contraindicated, as it was in our patient. MRI is useful in delineating fluid-filled structures from benign and malignant sinus tumors.

Treatment includes decompression of the expanded sinus and correction of ostial obstruction. Traditionally, sinus mucoceles have been decompressed via an open approach. Contemporary management, however, employs advanced endoscopic techniques, including image-guided surgery. The newer approach has rendered the open techniques somewhat obsolete.

Suggested reading

Bockmuhl U, Kratzsch B, Benda K, Draf W. Surgery for paranasal sinus mucocoeles: Efficacy of endonasal micro-endoscopic management and long-term results of 185 patients. Rhinology 2006; 44(1): 62-7.

Jason S. Hamilton, MD; Sofia Avitia, MD; Ryan F. Osborne, MD

From the Osborne Head and Neck Institute, Los Angeles.