Pathological lesions of the third ventricle

The walls of the third ventricle contain a large variety of tissues, and th e pathological processes in this area are extremely varied The pathological lesions encountered in the third ventricle ave analyzed with interest to t heir incidence in the national series. Colloid cysts have a single layer of epithelial cells, mimicking the bronchus epithelium, which may reveal thei r probable endodermic origin. Xanthogranulomas are not true neoplasms but a re only reactional to local hemorrhages. Histological diagnosis may be diff icult for glial tumors if the biopsy sampling is insufficient: pilocytic as trocytomas can be overgraded and confused with high grade astrocytomas. Sub ependymomas should be separated from ependymomas, and giant cell subependym al astrocytomas are specific lesions occurring in tuberous sclerosis. Crani opharyngiomas often show a papillary type when located in the third ventric le. Germinal tumors are associated with immunological markers. The variety of the encountered lesions in the third ventricle needs a close collaborati on between neuropathologists and neurosurgeons, and a confrontation of hist ological data with clinical and radiological data.