Histopathological examination revealed a pituitary tumor of null cell origin (negative hormone, alpha-subunit and transcription factors: steroidogenic factor [SF-1], T-box family member TBX19 [T-PIT], and pituitary-transcription factor 1 [PIT-1]), synaptophysin (+), a Ki-67 index of 11%, and 7 mitoses/10 high-power fields (Fig. 2A-2B). This evidence concerns the gene POU1F1 and pituitary tumor.