A 21-year-old man was admitted to hospital because of recent anosmia a
nd liquorrhoea. He also complained of moderate headache and concentrat
ion problems in the past few years. On CT scan and MRI scans a big sub
frontal process was seen, partially solid and partially cystic. Neuros
urgical and histological findings proved that the lesion was an osteom
a of the anterior skull base, concomitant with an intradurally extendi
ng mucocele.