Virtual Microscope
A 45 year-old man with an enhancing parietal mass
Elizabeth Rushing, M.D., Col.
Department of Neuropathology and Ophthalmic Pathology, Armed Forces Institute of Pathology, Washington, D.C.
Last updated: March 31, 2007
Clinical Information: The patient was a 45 year-old man with headache. MRI reveals a 3.0 cm intra-axial parietal mass with substantial edema tumor in surrounding parenchymal tissue.
Diagnosis: Anaplastic ependymoma, WHO grade III.
Pathology: The pathology of this case is classic. There are two fragments on the slide. The rounder one is a rather densely packed glial neoplasm with classific perivascular arrangment of tumor cells and find cytoplasmic processes with coronary arrangement pointing to a thined walled blood vessels, the so-called pseudorosettes. The tumor cells appear rather monotonous at scaning or low magnification. On higher magnification, they have a moderate degree of atypia and nuclear enlargement. Mitotic figures are frequently seen. The elongated piece of tissue has tumor cells rather similar in morphology to the other piece but there is extensive necrosis.
If you search carefully, there are small clusters of cells that are positive for epithelial membrane antigen (EMA). Immunohistochemistry for glial fibrillary acidic protein (GFAP) demonstrates a patchy expression. Interestingly, the fragement with more necrosis are more immunoreactive. Many of the cells are positive for p53. Immunohistochemistry for Ki67 demonstrate a very high labeling index. In some small hot clusters, the labeling index is close to 50%.