[The occurrence of tyrosine hydroxylase-immunoreactive neurons in a parietal lobe ganglioglioma].

A parietal lobe ganglioglioma in a 61-year-old male was investigated ultrastructurally and immunohistochemically, using antiserum against tyrosine hydroxylase (TH), a rate-limiting enzyme of the catecholamine (CA)-synthesizing pathway. On light microscopy, the tumor was composed mainly of neuronal and astrocytic cells. The neuronal cells had typical round vesicular nuclei with prominent nucleoli and showed abundant cytoplasm with variable amounts of Nissl bodies. Bi-nucleated neuronal cells were occasionally found. The astrocytic cells had eosinophilic cytoplasm of variable shapes and hyperchromatic small nuclei. Electron microscopy revealed numerous dense core vesicles (DCVs) in the neuronal cytoplasm and processes. Immunohistochemically, TH-immunoreactive neuronal cells were found sporadically in the tumor tissue. They were often binucleated or multinucleated. The presence of TH-immunoreactive neuronal cells in the present case is of interest in considering the origin of neuronal cells in ganglioglioma. Some investigators have considered that they may arise from the ectopic autonomic neuronal cell nests in view of the presence of DCVs. However, Gasper et al. have recently demonstrated the presence of TH-immunoreactive neurons in the normal human cerebral cortex. Therefore, it may also be possible to consider that TH-immunoreactive neuronal cells in this tumor originated from a certain dysgenetic focus containing such TH-immunoreactive neurons in the developmental stage.