1/2. Infratentorial giant cell ependymoma: a rare variant of ependymoma.We describe a giant cell ependymoma occurring in a 50-year-old man. The mass was located in the posterior aspect of the foramen magnum, extending from the cerebellar tonsil to the upper cervical spine. The tumor was a highly cellular neoplasm showing biphasic histology. Diffuse sheets of non-cohesive atypical giant cells, having eccentrically located single or multiple nuclei and plump eosinophilic cytoplasm, partly infiltrated the desmoplastic inflammatory stroma. Parts of perivascular pseudorosette-forming or pseudopapillary areas were composed of atypically elongated cells, which looked like conventional anaplastic ependymoma. There was a transitional area between two patterns. Numerous mitoses and focal necrosis were observed. Immunohistochemically, the tumor cells were immunoreactive for glial fibrillary acidic protein, vimentin, S-100 protein, and CD99. None of the tumor cells showed immunoreactivity for epithelial membrane antigen except for the intracytoplasmic lumen of a few vacuolated cells. Ultrastructurally, tumor cells were ependymal in nature; we noted cytoplasmic intermediate filaments and intercellular microrosettes with microvilli, cilia, and long zonula adherens. The features of this tumor, e.g. its superficial location, mixed giant cells, perivascular pseudorosettes or papillaries, complicated its differentiation from rhabdoid/papillary meningioma. However, immunohistochemistry and electron microscopy confirmed the diagnosis of ependymoma. The giant cell variant should be included in the subclassification of the ependymoma.- - - - - - - - - - ranking = 1keywords = giant (Clic here for more details about this article) |
2/2. prenatal diagnosis of a giant congenital primary cerebral hemangiopericytoma.Congenital primary intracranial hemangiopericytomas are exceptionally rare tumors. We present a case of a fetus, with the prenatal sonogram at 33 weeks of gestation revealing a large cerebral tumor. Because of the enlarged head, a cesarean section was performed. The tumor was confirmed by postnatal ultrasound, magnetic resonance imaging (MRI) and biopsy. Elevated intracranial pressure and hemorrhage led to death on the 11th day. autopsy revealed a 10x9 cm large inhomogeneous tumor located centrally, mainly in the posterior fossa. histology showed a hypercellular and hypervascular tumor with extended necrosis and high mitotic rate. The tumor cells were positive for vimentin and CD34 antigens and negative for several neurological markers, desmin and CD31. The diagnosis of a congenital primary cerebral hemangiopericytoma was confirmed.- - - - - - - - - - ranking = 0.5keywords = giant (Clic here for more details about this article) |