5/2/2006 Case 1: Anaplastic glioneuronal tumor

Clinical History:

The images showed a tumor with a variety of patterns, made up mostly of relatively small cells with round "oligodendroglioma"-like nuclei, often surrounding small to medium-size blood vessels in single layers in a pseudopapillary fashion. Other areas were more diffuse. There was definite synaptophysin immunopositivity, and electron microscopy showed some possible dense core neurosecretory granules and neurite-like processes with parallel arrays of microtubules. Some of the tumor appeared low grade, but there were focal areas with suggestions of vascular hyperplasia and there was some appreciable proliferative activity with Ki67/MIBl immunostains.

Diagnostic Notes:

Initial diagnosis was one of "Anaplastic Glioneuronal Tumor of indeterminate prognosis". The case was called "Fibrillary Astrocytoma" at Children's Hospital of Philadelphia, and "Low grade glioma, pilomyxoid astrocytoma" at Hopkins, with some question also raised about an "oligodendroglioma" component. Opinions from those present at the meeting included "Papillary Glioneuronal Tumor", "Angiocentric Neuroepithelial Tumor", and "Anaplastic Glioneurocytoma". There followed an extensive discussion of the current state of classification of glioneuronal neoplasms, with broad agreement that this needed to be improved. The WHO is now out of date with regard to a number proposed entities, all of which share glioneuronal differentiation with some neurocytoma-like cells, all of which are extra-ventricular neoplasms. As the above range of diagnoses indicates there have been multiple proposed "entities", which some may later wish to "lump" while others may wish to retain as "split".

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