Endocrine Abstracts

Gonadotroph pituitary tumors (GnPiT) account for ~40% of pituitary tumors surgically treated and 70-75% of non-functional pituitary tumors. Functional gonadotropin-secreting tumors are rare and clinical manifestations vary according to the age and sex of the patient. They are benign tumors which, due to their silent nature, can grow and invade surrounding structures, making complete resection impossible and leading to recurrence in ~30% of cases.

Objective: The aim of our study is to provide a comprehensive, up-to-date characterization of either clinically silent/whispering or functional GnPiT.

Patients and Method: Retrospective study of 151 adult patients (105 men and 48 women) with a histological diagnosis of GnPiT, operated at our referral pituitary center from January 2020 to December 2022. Clinical, hormonal, tumoral and pathological data were analyzed according to sex and age.

Results: Diagnosis was incidental in about half of patients. A different distribution of tumors based on age was found, with a normal distribution in male (median age 63 years (25-89)), and a bimodal one in female (median age 58 years (26-84)). Only one tumor showed a functioning hormonal secretion responsible of an ovarian hyperstimulation syndrome in a 40-year-old woman; while 8 tumors (1 F and 7 M) showed a possible, but clinically silent, secretory activity. FSH was elevated in all cases, accompanied by LH and testosterone in one. Hypersecretion did not cause a subsequent clinical picture, and tumors did not appear to behave differently compared to the non-secreting one. Four histological subtypes were described according to hormonal immunohistochemistry: FSH-LH (n=96), FSH (n=41), LH (n=6), non-immunoreactive (NIR; n=8). Sex-related distribution did not find relevant differences (FSH-LH: 65.62% M, 34.38% F; FSH: 75.60% M, 24.40% F; LH: 83.33% M 16.67%; NIR: 50% M, 50% F). No differences were found according to histological subtypes, especially regarding FSH and LH secretion. Spearman correlation analysis showed a weak, but significant, correlation between serum FSH and FSH staining (r: 0.21, p: 0.015), none between serum FSH and transcription factors SF1 and GATA3, and a weak, but significant, correlation between LH staining and GATA3 (r: 0.34, p: 0.0002).

Conclusion: Our results provide information possibly useful in future studies for a better understanding of the GnPiT subtype. Gonadotropins hypersecretion remains a rare finding and, when present, is mostly silent and not linked to specific pathological features. Moreover, a thorough pathological assessment did not highlight relevant differences among the four subgroups identified in this work.