To Örebro University

INTRODUCTION: This study aims to describe whether the clinical behaviour of nonfunctioning pituitary neuroendocrine tumours/nonfunctioning pituitary adenomas (NF-PitNETs/NFPAs) is affected by pituitary cell lineage differentiation, focusing on patients with silent corticotroph tumours (SCTs) and silent gonadotroph tumours (SGTs).

METHODS: Patients (N = 101) who underwent primary surgery for NF-PitNETs/NFPAs from August 2014 to March 2020 at Uppsala University Hospital were included. Data on sex, age, MRI, pituitary function and immunohistochemical analysis of anterior pituitary hormone and transcription factor expression, were explored.

RESULTS: Seventy-three patients had SGTs, and 18 had SCTs. Binary logistic regression revealed that having SCT versus SGT (OR 6.41 (CI: 1.20-34.42), p = 0.03), being older at the time of surgery (OR 1.07 (CI: 1.02-1.12), p = 0.01), and having a larger preoperative tumour volume (OR 1.17 (CI: 1.04-1.32), p = 0.01) were associated with an increased likelihood of postoperative pituitary failure. Patients with preoperative pituitary failure were older at the time of surgery (p = 0.01) and more often had preoperative elevation of prolactin levels (p = 0.01) than patients without preoperative pituitary failure. SCT patients were younger at the time of surgery than SGT patients (p = 0.003), but no significant difference in preoperative tumour volume was detected.

CONCLUSION: The results indicate that cell lineage differentiation in NF-PitNETs/NFPAs influences clinical behaviour. Patients with SCTs were younger at the time of surgery, and harbouring a SCT was associated with an increased likelihood of having postoperative pituitary failure. These findings emphasise the importance of routine immunohistochemical analyses of anterior pituitary hormone and transcription factor expression to identify silent corticotroph tumours.