MTOR and histiocytic sarcoma: Previous studies characterized two subpopulations of astrocytes: ‘reactive’ cells, which are large and vimentin positive and reveal mTOR activation, and ‘gliotic’ astrocytes, which are smaller, do not show mTOR activation, and resemble gliotic astrocytes found in temporal lobe epilepsy with hippocampal sclerosis (TLE-HS) (Sosunov et al., 2008, 2012).