Germinomas of the brain. Light and electron microscopic study. A report of seven cases

The authors report seven cases of intracerebral germinomas studied on autopsy and/or biopsy material. Electron microscopy was done in five cases. Tumors were located on the middle line of the brain (pineal area, suprasellar region, third ventricle). Light microscopic features were stereotyped with PAS + round tumor cells and inflammatory mononuclear cells. By electron microscopy, fenestrated nucleoli, glycogen storage and annulate lamellae were always found, as well as a striking macrophagic activity of histiocytes. This immune reaction is supposed to contribute to the relatively favorable prognosis of these original brain tumors.