Using whole-scan quantification of S100B IHC staining, we first confirmed an overall loss of S100B + FS cells in the majority of our PitNETs compared to normal APG and to adjacent APG, with 80% of these tumours having < 1% S100B + cells, and 35% having < 0.1% S100B + cells. The gene discussed is S100B; the disease is neoplasm.