The immunohistochemistry and ultrastructure of ganglioglioma with chromosomal alterations: a case report.

Ganglioglioma, together with its counterparts-ganglioneuroma and gangliocytoma are relatively uncommon neoplasms of the brain composed of neoplastic neurons (ganglion and ganglioid cells) and glial cells. We report here a case of ganglioglioma studied by electron microscopy. The case was further characterized by peculiar chromosomal alterations, 46,XX[6]/43,XX[1], der(1)t(1;5)(q21;q12), der(8;13)(q10;q10),-9,i(10)(q10). Routine light microscopy revealed mixed neuro-glial tumor composed of pilocytic astrocytes with abundant Rosenthal fibers and relatively numerous ganglion cells. The latter were immunoreactive with antibodies (Abs) against synaptophysin and neurofilament protein (NFP). Anti-NFP Abs also immunostained numerous distorted axons embedded in the tumor mass. Some of these showed bullous swellings and thus were analogous to dystrophic neurites or spheroids. Ganglion cells were characterized by abundant intracytoplasmic dense-core vesicles, absence of intermediate filaments and numerous microtubules. Occasionally a close apposition of ganglion cells and Rosenthal fibers were seen. Dense-cored vesicles were pleomorphic and ranged in diameter from small synaptic vesicles to large lysosome-like neurosecretory granules. The former occasionally formed characteristic dumbbell shapes. Neoplastic astrocytes were identical to those of other glial tumors of astrocytic lineage; numerous Rosenthal fibers were frequently seen.