The classifications are based on the immunohistochemical profile and transcription factors (TFs) from which the tumor originates (PIT-1, pituitary-specific POU-class homeodomain transcription factor; SF1, steroidogenic factor 1, and TPIT, T-box family member TBX19), which makes it possible to identify so-called silent PitNETs that do not produce clinically detectable amounts of hormones but have a specific molecular phenotype. Here, TBX19 is linked to neoplasm.