Immunohistochemical localization of vimentin and S-100 antigen in small acoustic tumors and adjacent cochlear nerves.

To clarify the involvement of cochlear nerves in small acoustic tumors, we used immunoperoxidase techniques to determine the presence and distribution of vimentin and S-100 antigens in two acoustic tumor specimens and a transected vestibular nerve. Schwann cells and acoustic tumor cells failed to react positively with monoclonal antibody to vimentin. Reaction was observed in mesenchymal-appearing cells within both the normal nerve and the acoustic tumors, predominantly in association with blood vessels. Normal schwann cells and acoustic tumor cells reacted with polyclonal antibody to S-100 antigen with a similar, uniform distribution. Mesenchymal-appearing cells did not react with antibody to S-100. Immunostaining of a vestibular nerve from a Meniere's disease patient, used as a control, did not differ significantly from nerves adjacent to acoustic tumors. Because tumor cells and normal schwann cells stained similarly with antibody to S-100, it was not possible to establish with certainty if tumor cells invaded adjacent nerves.