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Published online by Cambridge University Press: 25 May 2018
Anaplastic ependymomas are relatively uncommon, WHO grade III tumours that can occur in any location of the central nervous system. Low, as well as high grade tumours may show an additional component, most frequently cartilage or bone. Ganglionic differentiation has been demonstrated in only very few cases, usually young individuals. The purpose of this communication is to describe six examples of anaplastic ependymomas with a definite ganglionic component. All tumours were supratentorial and occurred in adults, 36-81 years of age. With the exception of one with a cystic component, all showed a diffuse MRI pattern and variable enhancement. All tumours displayed necrosis, vascular proliferation and marked pleomorphism, due to a mixture of epithelioid, giant, rhabdoid and gemistocytic, as well as clear and undifferentiated cells. Immunohistochemistry revealed reactivity for EMA (often atypical), GFAP and markers of neuronal differentiation, usually synaptophysin and chromogranin. All displayed high MIB-1 and occasional P53-positive nuclei. Two cases showed sarcomatous differentiation with desmin, smooth muscle actin and very rich reticulin staining. Electron microscopy revealed “zippering” intercellular junctions, basal bodies and cilia. Neuronal differentiation was expressed by neurosecretory granules and/or rich endoplasmic reticulin, large nuclei with nucleoli, and rare neuritic processes with microtubules. Differentiation of these rare tumours from glioblastomas might be important for the future development of tumour-specific molecular therapies. Electron microscopy is highly recommended for correct diagnosis of atypical variants of Anaplastic Ependymoma.