Papillary glioneuronal tumor

Tumors of mixed glioneuronal type are well recognized in the central nervou s system. The most common examples of these lesions include gangliogliomas and dysembryoplastic neuroepithelial tumors. Recently, unusual examples of these lesions have been described, including the papillary glioneuronal tum or. This report describes a histologically similar-appearing lesion arising in the left parieto-occipital lobe of an 18-year-old man who presented wit h headaches and difficulties with vision. Imaging studies noted a large cys tic neoplasm marked by a peripheral rim of enhancement. The patient underwe nt gross total resection of the tumor, which histologically was marked by a mixture of glial (glial fibrillary acidic protein-positive) and neural (sy naptophysin-positive) components. Architecturally, the tumor was notable fo r a focal pseudopapillary pattern. Papillae were lined by predominantly gli al cells, with intervening areas occupied by neurally differentiated cells. Mitotic activity, vascular proliferation, and necrosis were not noted. A M IB-1 labeling index of 1.1% was seen. p53 immunoreactivity was not observed . This report adds further evidence supporting the existence of this unusua l mixed glioneuronal tumor of the central nervous system.