Pneumosinus dilatans is a rare disease of unknown etiology characterized by expansion of 1 or more paranasal sinuses. The lesion includes an abnormal enlargement of the sinus cavity, but no evidence of bony destruction or pathological changes of the underlying mucosa. In some reports the symptoms involve compression of the optical nerve and associations with meningiomas or arachnoidal cysts. Osteoplasty or decompression surgery seem to be the only effective treatments