Glomus tumors of the temporal bone: electron microscopic and immunohistochemical evaluation

Glomus tumors arising in the temporal bone are now recognized as being part of the diffuse neuroendocrine system. Material from 12 glomus tumors was studied by means of electron microscopic and immunohistochemical techniques to determine whether there was an association between tumor size, patient age, and the neuroendocrine functions of these tumors. Electronmicroscopic evaluation (seven tumors) revealed a highly variable concentration of neurosecretory granules. Immunohistochemical staining (nine tumors) demonstrated that glomus tumors do arise from neural ectoderm and that they all contain serotonin. The concentration of serotonin seems to correlate with the concentration of neurosecretory granules seen on electronmicroscopy. In addition, higher levels of serotonin were found in two patients who were in their late sixties. It is possible that some of the neuroendocrine activity associated with glomus tumors could be the result of the release of serotonin.