Introduction: Inverted papilloma is a rare benign tumor of the nasal fossa, which usually originates from its lateral wall. Only 5% of cases demonstrate exclusive sinus involvement. Primary sphenoid sinus involvement is even rarer. Although considered a benign lesion, the tumor has a potentially invasive nature and has also been found to have an associated malignancy rate of 7 to 15%.

Objectives: To report a case of inverted nasal papilloma originating in a rare location: the sphenoid sinus.

Resumed Report: a 56-year-old woman, presented to our outpatient clinic complaining of frontal headache, occasional otalgia and recent forgetfulness. She was initially evaluated by a neurologist and then submitted to a head magnetic resonance imaging. A lesion was found to be filling both sphenoid sinuses. Sinus computed tomography showed an opacified sphenoid sinus with apparent bony integrity. The patient underwent sphenoidotomy through a transnasal endoscopic approach. A bleeding papillomatous lesion was identified. A biopsy was performed and histopathologic study suggested inverted papilloma. The lesion was then completely resected. The patient has been followed for 60 days after surgery; no signs of recurrence were found upon flexible nasofibroscope examination.

Conclusion: Inverted Papilloma exclusively involving the sphenoid sinus is a rare entity. Non specific symptomatology and Clinical presentation make this kind of tumor a diagnostic and therapeutic challenge. The Endoscopic Sphenoidotomy has been the treatment of choice. Close follow-up is required in order to detect possible recurrences and malignant transformation.