[Extemporaneous histopathological examination in neurosurgery. Report on 500 cases]

The authors review 500 extemporaneous histopathological examinations done in a neurosurgical unit over a 16-month period. The following four questions are asked by the neurosurgeon: is there a tumor? is it a primary or secondary one? what variety is it? what is its degree of malignancy? The percentage of errors was respectively: 2 per cent, 2.2 per cent, 8.8 per cent and 7.4 per cent, or roughly, a percentage two times lower than in a series from the same laboratory done before the use of the low-temperature microtome. It especially seems that the tumoral variety is often determined accurately in meningiomas, neurinomas, medulloblastomas and craniopharyngiomas. In gliomas the variety is often more difficult to accurately affirm, and especially the "grade" of malignancy. The authors analyse the problems raised by the different types of tumors.