"Perivascular pseudorosettes are a common histologic feature of central nervous system ependymomas. They represent sections through papillary structures composed of tumour cells arranged radially around a central vessel. Between the central vessel and the tumour cells is a relatively microscopically clear region filled with cytoplasmic processes that are strongly positive for GFAP 1,2. In myxopapillary ependymomas, myxoid material will also be present within this clear space, sometimes forming microcysts 1."
"EMA positive perinuclear dot sometimes forming intracytoplasmic microrosettes"