<prompt> Answer this question truthfullyWhat is gemistocytic astrocytoma? This is already proper English.  <response>: <reason> It is important to note that other gliomas e.g. fibrillary astrocytoma and oligodendrogliomas can have occasional gemistocytes, without being designated a gemistocytic astrocytoma. A cut off of 20 of the tumor cells being gemistocytes, is used before designating a lesion to be gemistocytic astrocytoma. Gemistocytic astrocytoma must be differentiated from:Fibrillary astrocytoma Protoplasmic astrocytoma Oligoastrocytoma Stroke Cerebritis Herpes simplex encephalitis Anaplastic astrocytoma Oligodendroglioma Angiocentric glioma 