[Brain biopsy in systemic diseases].

In systemic diseases, brain biopsy is an exceptional diagnostic procedure which must be restricted to those rare forms involving only the central nervous system, at least clinically, and when a treatable disease is suspected the treatment of which requires a precise histological diagnosis. According to the clinical presentation and radiological appearance, an open biopsy or a stereotactic biopsy under radiological control will be proposed. In this paper, will be reviewed the indications and neuropathological findings in systemic amyloidoses extending to the central nervous system, cerebral angiitis, sarcoidosis, Whipple's disease, Langerhans'cell as well as non-Langerhans'cell systemic histiocytoses and paraneoplastic encephalomyelitis.