neuroplex
New York Association of Neuropathologists
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 The WHO is now out of
date with regard to a number proposed entities, all of which share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".
