Tactile-like corpuscles in neurofibromas: immunohistochemical demonstration of S-100 protein.

Tactile-like corpuscles in neurofibroma tissues were examined by the indirect immunoperoxidase method using rabbit anti-S-100 sera. In all five cases examined, positive staining was observed in their constituent cells, both in the flattened cytoplasm and nuclei. On examination of the normal peripheral nervous system, positive staining was exclusively confined to Schwann cells in the nerve bundles and Schwann-related cells such as lamellar cells in the Meissner corpuscle, whereas staining was negative in perineurial cells. Electron-microscopic examination showed ultrastructural similarity between constituent cells of the tactile-like corpuscles in neurofibroma and lamellar cells in the Meissner corpuscle. These findings may indicate Schwannian nature of the tactile-like corpuscles.