Dehiscence of the lamina papyracea of the ethmoid bone: CT findings.

PURPOSE To describe the CT findings characterizing dehiscence of the lamina papyracea. METHODS Axial and coronal CT scanning of the paranasal sinuses was performed on 783 patients. RESULTS Dehiscence of the lamina papyracea was noted incidentally in six patients. In all cases dehiscence was characterized by protrusion of orbital fat through a gap in the anterior ethmoid. The posterior limit of the dehiscence was always the basal lamella. The anterior limit varied. CONCLUSION CT scans are often taken to detect polyps or assess chronic sinusitis. Awareness of dehiscence of the lamina papyracea is important to avoid misdiagnosis as infectious or tumoral process and possible injury of the orbit during endoscopic surgery.