Orbital Mucocele

Abstract

Three patients with unusual orbital mucoceles all presented with proptosis and ptosis. None had a history of trauma or sinus infection. In each case, computerized tomography (CT) demonstrated a well-defined, homogeneously isodense mass in the superior orbit, which displaced the globe inferiorly. There was no apparent continuity between the orbital mass and the sinuses. In Case 2 the administration of contrast medium showed enhancement of the rim of the lesion. Magnetic resonance imaging (MRI) in Case 3 clearly revealed the location and soft tissue characteristics of the lesion, and the isointense nature of the mass. Orbitotomies by the transcranial supraorbital approach, which is considered to be the procedure of choice for superior orbital lesions, disclosed cysts containing mucinous fluid; all three were excised. In Case 1, the cyst was separated from the frontal sinus by the ossified wall. In Cases 2 and 3, the cyst communicated with the anterior ethmoid sinus through a small orifice in the medial orbital wall. Histological study of the cyst walls demonstrated columnar or cylindrical ciliated epithelium, which is compatible with mucocele. The mechanisms of mucocele formation and the role of CT and MRI in differentiating this lesion from other intraorbital lesions are discussed.