Ganglioneurocytoma: distinctive variant of central neurocytoma.

Reported herein is a case of central neurocytoma with differentiation toward ganglion cells, considered to be a typical case of ganglioneurocytoma. Tumor cells of various degree of differentiation toward ganglion cells were intermingled with typical neurocytoma cells in a fibrillary background, with transition of tumor cells from typical neurocytoma cells to differentiated ganglion cells evident throughout the tumor. The tumor cell nuclei were positive for NeuN. Fine granular positivity for synaptophysin was seen in the cytoplasm of the tumor cells, and background fibrils and the cytoplasm of some ganglioid cells were positive for neurofilament. Several cases of central neurocytoma with ganglioid cells have been reported, with some diagnosed as ganglioneurocytoma. However, histopathological details and persuasive figures have been lacking. It is considered that the diagnosis of ganglioneurocytoma should be applied to tumors displaying the following characteristics: (i) clinical aspects such as location, demarcation and growth rate consistent with neurocytoma; (ii) transition between neurocytoma cells and ganglion cells; and (iii) ganglioid cells distributed throughout the tumors.