[Acoustic neuroma: a histopathological study].

In view of recent controversy concerning the preservation of hearing in acoustic neuroma surgery, a histologic study of the nerve-tumour interface was undertaken in order to investigate cochlear nerve involvement. Twelve intact acoustic neuromas were studied by means of Masson's trichrome stain, the Luxol fast blue technique, Verhoeff's stain and an immunohistochemical technique using monoclonal antibodies to human neurofilaments. In nine out of twelve specimens, macroscopically visible adherences were present between the cochlear nerve and the tumour. The microscopical correlate was found to be the absence of a clear cleavage plane between the cochlear nerve and the tumour on the one hand, and the presence of cochlear nerve fibers, surrounded by tumoural cells, past the assumed nerve-tumour interface on the other hand.