A sensitive and specific diagnostic panel to distinguish diffuse astrocytoma from astrocytosis: chromosome 7 gain with mutant isocitrate dehydrogenase 1 and p53.

One of the major challenges of surgical neuropathology is the distinction of diffuse astrocytoma (World Health Organization grade II) from astrocytosis. The most commonly used ancillary tool to solve this problem is p53 immunohistochemistry (IHC), but this is neither sensitive nor specific. Isocitrate dehydrogenase 1 (IDH1) mutations arecommon in lower-grade gliomas, with most causing a specific amino acid change (R132H) that can be detected with a monoclonal antibody.