A case of anaplastic clear-cell ependymoma presenting with high erythropoietin concentration and 1p/19q deletions

Case of Clear Cell Ependymoma Successfully Treated with Preoperative Embolization

Objective

Clear cell ependymoma (CCE) is known to be very similar to hemangioblastoma (HB) in regards to neuroimaging and histopathology. We report a rare case of CCE in which successfully underwent preoperative embolization with a prior diagnosis of HB.

Case Presentation

A 58-year-old woman presented with vertigo for several months. MRI showed the right cerebellar tumor mimicking solid HB. DSA revealed the hypervascular tumor supplied by branches of the posterior inferior cerebellar artery (PICA). To reduce intraoperative bleeding, preoperative embolization was performed using n-butyl-2-cyanoacrylate (NBCA). A flow-guided microcatheter was guided to the proper feeders, and diluted NBCA was injected. Sufficient devascularization was achieved. The tumor was totally resected with minimal blood loss the next day. Postoperative pathological diagnosis was CCE.

Conclusion

This is the first report that preoperative embolization was performed to CCE with careful techniques and recent advanced devices. Since CCE has a poorer prognosis, preoperative embolization for safety total resection may be more important.

Cerebellar ependymoma with overlapping features of clear-cell and tanycytic variants mimicking hemangioblastoma: a case report and literature review

BACKGROUND

Imaging and histology of clear-cell ependymoma and cerebellum-based hemangioblastoma are similar; distinguishing between them is a diagnostic challenge.

CASE PRESENTATION

A 62-year-old Chinese woman presented with an intermittent headache of 8 years' duration. Computed tomography and magnetic resonance imaging revealed a mass in the cerebellum. Neurological imaging suggested hemangioblastoma (HB). Histologically, the tumor included cellular and paucicellular areas, in which cells were arranged in nests or diffusely distributed; and a highly vascular area, in which tumor cells were arranged in clusters and separated by capillaries. At low magnification, the tumor mimicked cellular HB, but at high magnification, tumor cells showed clear cytoplasm instead of the vacuolated cytoplasm typically observed in HB. Moreover, spindly, bipolar elements resembling tanycytes were observed within the nest structures. Although these features indicated the possibility of ependymoma, neither true ependymal rosettes nor an ependymal-lined profile was observed. The tumor was characterized by prominent vascularity, but glomeruloid formation was absent. We saw pleomorphism in foci of some tumor giant cells, but pathologic mitosis and palisaded necrosis were absent. Most tumor cells were positive for glial fibrillary acidic protein and S100. Epithelial membrane antigen was expressed with a paranuclear dot-like or a ring-like pattern. The Ki-67 index was approximately 2%. Considering the patient's symptom, neurological imaging, and pathological findings, she was diagnosed as cerebellar ependymoma (WHO grade II).

CONCLUSIONS

Here, we report a case of ependymoma with overlapping clear-cell and tanycytic features, and review the literature to evaluate its real incidence. Pathologists should consider this rare diagnosis when confronted with a similar presentation.

Oligodendroglioma (WHO grade I) in a young epilepsy patient: a specific entity lying within the spectrum of dysembryoplastic neuroepithelial tumor?

We studied a frontal lobe subcortical cystic tumor that had been resected from a 13-year-old girl with a 3-year history of intractable partial seizure. Currently, more than 13 years after surgery, the patient remains recurrence-free and has no neurological deficits. Histological examination showed that the tumor was non-infiltrating and paucicellular with a mucinous matrix, and consisted of fairly uniform small cells with round to oval nuclei. Within the mucinous matrix, the tumor cells were often arranged in pseudorosettes around small blood vessels. Mitotic activity and necrosis were absent, with a Ki-67 labeling index of <1%. Based on the immunohistochemical and ultrastructural findings, the constituent tumor cells were considered to be those of oligodendroglioma, including mini-gemistocytes and gliofibrillary oligodendrocytes. No neuronal elements were identified. Features of cortical dysplasia (FCD Type 1) were evident in the cortex covering the lesion. The surrounding white matter also contained a significant number of ectopic neurons. The entire pathological picture appeared to differ somewhat from that of ordinary oligodendroglioma (WHO grade II). Considering the clinical and pathological features, the present unusual oligodendroglioma appeared to represent a previously undescribed form of oligodendroglioma (WHO grade I) lying within the spectrum of dysembryoplastic neuroepithelial tumor (DNT; WHO grade I). Simultaneously, the present oligodendroglioma also raises the question of whether or not oligodendrocyte-like cells of DNTs truly show neurocytic differentiation.