[Pneumosinus dilatans--general considerations and a case report].

The term "pneumosinus dilatans" was coined by Benjamin in 1918 in his description of ballooning hyperpneumatization of the frontal sinus. The term was use later on for excessive pneumatization of individual or several paranasal sinuses, with or without local compressive signs. Inspite of numerous publications, the phenomenon of pneumosinus dilatans of paranasal sinuses never became particularly popular. The diagnosis of sphenoid pneumosinus dilatans in particular was difficult to establish by conventional radiological methods and demonstration of the indirect signs of a compressive mechanism was almost impossible prior to the introduction of thin section CT. The etiology and pathogenesis of pneumosinus dilatans were a matter of speculation and remained unsatisfactory to researches and clinicians. A 28-year-old male had a six-year history of scotoma and loss of the temporal visual fields for both eyes; he was admitted to Ophthalmological Department with visual loss of the right eye. The section CT was performed and revealed massive hyperpneumatization of the sphenoethmoidal sinusal complex, extending into the right anterior clinoid process, causing narrowing of the optic canal, more marked on the right than on the left side. The final diagnosis was: Right eye - Vitreous hemorrhage. Pneumosinus dilatans.