Olfactory colloid cyst: Case report and review of extraventricular colloid cyst literature

Objective A rare case of an extraventricular colloid cyst located in the olfactory groove extending downward into the ethmoid sinus is presented. This is the second reported case in the world literature. Methods A 56-year-old-woman presented with a lesion that was causing hyposmia and cerebrospinal fluid rhinorrhea. The lesion was an extraventricular colloid cyst displacing the left olfactory nerve downward and eroding into the left ethmoid sinus. Results The lesion was excised, and the anterior skull base was reconstructed successfully via a unilateral subfrontal approach. Conclusions There were no complications, and the patient made a full recovery, with resolution of the cerebrospinal fluid rhinorrhea.