According to this classification, PitNETs are either functional (secreting) adenomas or Silent Pituitary Adenomas (SPAs), also called Non-functioning Pituitary Adenomas (NFPAs), which are non-secreting forms of pituitary adenomas, classified according to TF expression to silent PIT1, silent TPIT, silent SF1, or null cell tumors (5, 6). Here, SF1 is linked to adenoma.