Ethmoid pneumocele presenting with exophthalmos 15 years after endoscopic sinus surgery.

Introduction: A pneumocele is an abnormal dilation of an air-containing sinus beyond the normal margins of bone, with associated bony thinning. A delayed ethmoid pneumocele after sinus surgery has not previously been reported. Methods: A case report of a patient with a delayed ethmoid pneumocele after sinus surgery. The diagnostic workup, operative approach, and postoperative results were evaluated. Results: A 57-year-old female with a history of endoscopic sinus surgery 15 years prior presented with right eye proptosis and severe orbital and facial pressure. A maxillofacial computed tomography showed a markedly expanded air-filled right anterior ethmoid space with a dehiscent lamina papyracea, consistent with a pneumocele. Marsupialization of the pneumocele as well as a revision ethmoidectomy were performed, with a visible return of the orbital contents to a more natural position. The patient experienced worsened diplopia immediately postoperatively that resolved within two weeks. Conclusions: This case demonstrates that a pneumocele can present even years after endoscopic sinus surgery, and acute but temporary development or worsening of diplopia can result from surgical decompression of the pneumocele as the eye returns to its natural position.