SF1 and neoplasm: With the application of the 2017 WHO classification, 377 of the 397 cases (95%) null cell adenomas were reclassified as gonadotroph PAs/PitNETs due to positive SF-1 immunostaining in tumor nuclei, 10 cases (2.5%) were reassigned to the PIT-1 lineage (3 SGSA, 2 SGLA, 2 thyrotroph, 3 plurihormonal PIT-1 positive adenomas), and 4 cases (1%) were reclassified as T-PIT lineage cases (4 SGCA, Fig. 3).