Clear-cell Ependymoma of the Cerebellum: A Case Report

Anaplastic oligodendroglioma arising from the brain stem and featuring 1p/19q co-deletion

With respect to localization, oligodendrogliomas are characterized by a marked preponderance of the cerebral hemispheres. Outside these typical sites, any tumor histopathologically reminiscent of oligodendroglioma a priori is likely to represent one of its morphological mimics, including clear cell ependymoma, neurocytoma, pilocytic astrocytoma or glioneuronal tumors. This is particularly relevant as several of the latter are in principle curable by surgery. Among extrahemispherical sites, bona fide oligodendroglioma - as characterized by loss of heterozygosity (LOH) of chromosome arms 1p and 19q - so far has not been documented to occur in the brain stem. Here, we report the case of a 55-year-old female patient with an anaplastic oligodendroglioma (WHO grade III) of the brain stem and cerebellum diagnosed by stereotactic biopsy and featuring combined LOH of 1p and 19q. A morphological peculiarity was a population of interspersed tumor giant cells, a phenomenon that has been referred to as polymorphous oligodendroglioma. Our findings confirm the notion that - although very infrequently - true oligodendrogliomas do occur in the infratentorial compartment.

Supratentorial clear cell ependymoma mimicking oligodendroglioma : case report and review of the literature

Clear cell ependymomas (CCEs) are rare variants of ependymomas. Tumors show anaplastic histological features and behave as an aggressive manner. CCEs have a predilection for extraneural metastases and early recurrence, and they demonstrate characteristic radiographic features. These tumors should be radiologically and pathologically differentiated from oligodendrogliomas. On microscopic examination, CCEs are composed of sheets of cells and resemble oligodendroglioma. However, upon closer examination, the nature of CCEs can be detected earlier, resulting in prompt treatment of the tumor. Although we report only one case, we emphasize the importance of early diagnosis and treatment. Future description of more cases of these rare cancers is necessary to aid in their diagnosis and treatment.

Differentiation of clear cell ependymoma of the cerebellum from hemangioblastoma by thallium-201 single photon emission computed tomography-case report-

A 57-year-old man suffered from dizziness for about one year and truncal ataxia for about one month. Magnetic resonance imaging demonstrated a cystic tumor with a homogeneously enhanced mural nodule located in the cerebellar vermis. Computed tomography angiography revealed a hypervascular nodule. These findings were compatible with hemangioblastoma. Thallium-201 single photon emission computed tomography ((201)Tl-SPECT) showed moderately high uptake in the early phase and moderately high retention in the delayed phase, whereas hemangioblastoma shows almost no retention in the delayed phase. The patient underwent total removal of the tumor. The histological diagnosis was clear cell ependymoma (CCE). CCE is a rare subtype of ependymoma, which resembles hemangioblastoma in histological and neuroimaging findings, but is considerably more aggressive. (201)Tl-SPECT can provide useful information for the preoperative differential diagnosis of infratentorial CCE and hemangioblastoma.