Specimen labelled "intraventricular tumour": Atypical meningioma, predominantly fibroblastic, with brain invasion.
Final Diagnosis Comment:
main features are those of a meningioma, predominantly of the
fibroblastic type. In view of the mitotic figures, areas of necrosis,
hypercellularity, and prominent nucleoli, this intraventricular tumour
is best designated as an "atypical" meningioma.
invades brain. The appearance of the brain with clusters of cells with
round nuclei and anuclear zones with microcystic change is reminiscent
of a subependymoma. Thus, the possibility of there being two
co-existing intraventricular tumours (meningioma and subependymoma)
should be considered. It is also possible the findings in the brain
tissue are reactive ependymal/subependymal changes.
show a meningioma comprised of cells with elongated to round nuclei and
eosinophilic cytoplasm with ill-defined cell boundaries. There is
extensive collagen deposition within the tumour. Most of the tumour
nuclei are rather large and show prominent nucleoli. Mitotic figures
are seen within the tumour and usually number approximately 1-3 per 10
high-power fields. However, at least one area shows six mitotic figures
per 10 high-power fields. There are a few areas of microscopic
necrosis. In some areas the nuclei are quite crowded. In some regions
there is a tendency to whorl formation and there are areas with
psammoma body formation.
At the periphery of the tumour,
fragments of brain are evident. In these fragments of brain there are
clusters of cells with rounded nuclei and anuclear zones. Microcystic
areas are also evident in these regions.
shows the meningioma is positive for vimentin and focally positive for
epithelial membrane antigen, and negative for keratin. There is intense
positiviy in the brain for glial fibrillary acidic protein (GFAP)and
some process positivity for vimentin and keratin. The meningioma shows
scattered MIB1-positive nuclei, whereas the brain tissue shows only
occasional positive nuclei.