Arachnoidal cap cell hyperplasia of the intracanalicular optic nerve sheath

Fifty-two intracanalicular optic nerves from 26 consecutive cadavers at the Dade County Medical Examiner's Office were examined for arachnoidal cap cells three cells thick or greater. Twenty specimens (77%) fulfilled these criteria with predominant involvement of the inferior and lateral aspects of the optic nerve sheath. Twenty-four specimens (92%) had psammoma bodies, and 17 specimens (65%) demonstrated corpora amylacea. Psammoma bodies as well as corpora amylacea were found with increasing frequency with age. However, our study did not show that age was an absolute factor toward the development of arachnoidal cap cell hyperplasia. The factors that incite foci of arachnoidal cap cell hyperplasia to greater activity leading in occasional individuals to the development of a meningioma remain to be determined.