High-risk pituitary adenomas: lessons learned and summary on the eve of the new classification - a clinicopathologic case series from the referral pituitary center.

J. Kunicki*^a (Dr), M. Maksymowicz^b (Dr)

^a Department of Neurosurgery , Maria Sklodowska-Curie National Research Institute of Oncology,Warsaw, Poland, Warsaw, POLAND ; ^b Department of Pathology and Laboratory Diagnostics, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland, Warsaw, POLAND

* jkunickii@gmail.com

2017 WHO classification of pituitary tumors recognizes five categories of pituitary adenomas that are shown to be more clinically aggressive regardless of their histological grading: sparsely granulated somatotroph (SG-GH) adenomas, lactotroph macroadenomas in men, Crooke cell adenoma, silent corticotroph adenomas, and plurihormonal Pit-1 positive adenomas.
The purpose of this study was to describe epidemiology, patient characteristics, tumor features, and treatment outcomes associated with this arbitrary set group of adenomas.
Material and Methodes: The study is a retrospective analysis of patients records who underwent resection of pituitary adenoma at the tertiary referral center for pituitary tumors The Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, between 2015 and 2021. The pathological assessment of adenomas were done in accordance with the 2017 WHO classification for endocrine tumors and European Society of Endocrinology clinical guidelines.
Results: 987 patients underwent endoscopic transnasal surgeryfor pituitary tumors in evaluated time period. Among these patients, 145 (14.7%) adenomas were classified into the so called high-risk adenomas grupe. There were 59 female patients (40,6%) in the cohort. The most numerous group among high risk groupe were patients with sparsely granulated somatotroph (SG-GH) adenomas 47/145 cases (32.4%),nest thehre were lactotrophe tumors in men 40/145 ( 27.5%). Other tumor types were: silent corticotroph adenomas 38/145 ( 26.2%), plurihormonal Pit 1 positive adenomas - 11 cases (7.5%), Crooke's cell adenomas -11 cases (7.5%). There were 94 invasive tumors (64.8%); 26 (17.9%) tumors had elevated proliferative markers ( Ki67 >3 %,MI); There were 19 cases (13.1%) of tumors with both invasive and with proliferative activity (2B grade Raverot/Trouillas). There was significant difference among proportion of invasive tumors in high risk group vs other adenomas ( 64.8% vs 29%). There were no significant difference in number of reoperations, incidence of pituitary apoplexies, number of giant tumors. There were 6 (4.1%) cases fulfilling the ESE criteria for clinically agressive adenoma and 1 patient with transformation to pituitary cancer.
The high risk group of arbitrary set subgroup of adenomas is characterized by significantly higher incidence of invasion which reflects the results of surgical treatment and higher probability of recurrence or progression.

The author has declared no conflict of interest.