The biopsy shows very limited tissue with an aggregate of glial cells.These cells are unevenly distributed. No perivascular pseudorosettes or true rosettes are seen. The glial cells have mildly enlarged and hyperchromatic nuclei, small nucleoli and scanty cytoplasm. Elsewhere, there are some pigmented macrophages, suggestive of previous haemorrhage. No mitoses, microvascular proliferation or necrosis is identified. The tumour cells are GFAP positive. There is EMA perinuclear dot positivity in the cells (black arrows in Figure 1), in keeping with ependymoma. The Ki-67 index is 1%. IDH-1 immunostain is negative.
DIAGNOSIS: Ependymoma (WHO Grade II).