Case 629 -- A 25-year-old Woman with a Mass in the Hippocampus

Contributed by Xiaomei Ma, MD, Junhui Ge, MD, Liangzhe Wang, MD, Chunyan Xia, MD, Huimin Liu, MD*, Yuli Li, MD, Jin He, MD, Weijian Zhu, MD
Department of Pathology, Changzheng Hospital, Second Military Medical University
*Department of Pathology, Changzheng Hospital. No.415, Fengyang Road, Shanghai, 200003, China


A 25-year-old woman had a history of 4 episodes of epilepsy over two years without treatment. MRI showed that there was a solid circumscribed, hyperintense and nonenhancing tumor (Fig 1) measuring 6x4x4cm in the hippocampus. T1-weighted and T2-weighted scans showed mixed signals without calcification in the tumor and no peritumoral edema. The tumor was totally resected. Macroscopically, the surgical sample was bits and pieces. Histologically, the tumor included glial, neuronal and mixed glioneuronal populations. The spindle-shaped tumor cells showed diffuse growth and displayed characteristic angiocentric arrangements around small parenchymal vessels forming perivascular pseudorosettes. There were single or multilayered tumor cells arranged with ependymal features (Fig 2). The tumor cells of the hippocampal surface formed distinctive rosettes (Fig 3) which have not been previously described. The spindle tumor cells were bipolar with elongated nuclei and inconspicuous nucleoli. In some areas, the tumor cells were schwannoma-like (Fig 4). We could find single neurons interspersed within the tumor tissue. Necrosis and mitotic activity were absence. Immunohistochemistry was positive for GFAP (Fig 5), Vimentin and S-100 and negative for neurofilament protein, Syn, CgA and NeuN. EMA showed "dot-like" positive staining (Fig 6). The proliferation index was less than 1%. Epilepsy disappeared after the operation. We only follow-up four months till now and There was no evidence of recurrence on MRI at a four month follow-up.


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