We report a rare case of adenocarcinoma of the sphenoid sinus manifesting as extended skull base tumor. The patient included in the study was a 42-year old woman presenting with unilateral right symptomatology consisting of nasal obstruction, diplopia and hemifacial neuralgias. Clinical examination showed paralysis of the cranial nerve pairs V and VI. Brain scanner showed voluminous heterogeneous sphenoid and clival mass reaching the right cavernous sinus, with a peripheral tissue component at the level of the sphenoid sinus. Biopsy was performed under general anesthesia, through endonasal sphenoidotomy approach. Histological examination showed non-intestinal adenocarcinoma. The patient died due to impaired general condition occurred during examinations. Skull base adenocarcinomas mainly occur in the ethmoid bone. Sphenoid origin is exceptional. Radiological appearance is not specific and suggests malignancy. Diagnosis should be suspected in patients with aggressive tumor, even when it occurs in the midline skull base.