Collision tumor of anaplastic oligodendroglioma and gangliocytoma: a case report.

A 53-year-old woman presented with a rare case of coexistence of anaplastic oligodendroglioma with gangliocytoma manifesting as progressive disturbance of consciousness and left hemiparesis. Magnetic resonance imaging with gadolinium demonstrated the mass lesion consisted of a strongly enhanced area around the middle cerebral artery and less enhanced areas in the right temporal lobe, insula, and basal ganglia. She underwent subtotal resection of the tumor, resulting in improvement of her symptoms. Macroscopic and histological examination showed the tumor consisted of two distinct components, grayish soft tissue and yellowish hard tissue. The former consisted of cells with equal-sized round-to-oval hyperchromatic nuclei and perinuclear halo with microvascular proliferation and necrosis, and the diagnosis was anaplastic oligodendroglioma. The latter consisted of large and dysplastic neurons with marked nucleoli and basophilic cytoplasm containing Nissl bodies, with nonneoplastic glial cells in the stroma, and the diagnosis was gangliocytoma. Both lesions were distinct, but intermingled at the border. These two tumors apparently occurred as a collision tumor.