Mucocele of the anterior clinoid process: Case report

OBJECTIVE AND IMPORTANCE: Of the primary intracranial mucoceles, those aris ing from the optic canal or anterior clinoid process are extremely rare. To our knowledge, only five cases have been reported. The pathogenesis of muc oceles at this unusual site is unclear, but the previously reported cases s uggest that these mucoceles may originate from pneumatizing air cells in th e anterior clinoid processes. CLINICAL PRESENTATION: A 43-year-old woman presented with diplopia. Magneti c resonance imaging showed a small mass, compressing the optic nerve, in th e medial portion of the left anterior clinoid process. The medial portion o f the anterior clinoid process surrounding the mass was eroded and the bony margins of the mass were well corticated in computed tomographic scans. Th ere was no direct connection between any paranasal sinus and the mass cavit y, as assessed in imaging studies and intraoperatively confirmed. The patho logical diagnosis after the operation indicated a mucocele. CONCLUSION: Considering the absence of air cells in the anterior clinoid pr ocesses, the mucocele in this case might have originated from ectopic mucin ous tissue that appeared during the development of the optic canal, rather than from a pneumatizing air cell.