Plurihormonal Pit-1 Positive Pituitary Adenomas: a systematic review and single center series.

Abstract

PURPOSE\nThe 2017 WHO classification of pituitary adenomas identifies the plurihormonal PIT-1 positive adenoma (PP1) as a distinct subtype. Literature suggests PP1 encompasses the former class of Silent Subtype 3 adenoma (SS3), and may have an aggressive phenotype. This study summarizes the current clinical data on PP1 and SS3 tumors and compares this published data to a single institutional cohort.\n\n\nMETHODS\nMedline and Google Scholar were searched from 1990 to 2020 for clinical series of PP1 and SS3 according to PRISMA guidelines. Studies were included with pituitary pathology reported to be either PP1 or SS3 and if they reported clinical outcomes after a surgical intervention. To better define PP1 phenotype in comparison to non-PP1 pituitary adenomas, adenomas treated surgically at the authors institution from 2012-2019 were reviewed.\n\n\nRESULTS\nOf all tumors reported in the literature as PP1 or SS3, 99% were macro-adenomas and 18% were giant (>4cm). 31.8% of patients received radiotherapy. 22.9% of patients underwent multiple surgeries for their pituitary pathology. In the single-center experience reported here, 20 patients met criteria for the category of PP1. Compared to 1146 non-PP1 tumors, PP1 tumors did not show statistically significant differences in extent of resection, size, number of prior surgeries, future re-operations, rates of receiving radiotherapy, p53 staining, or MIB-1 labelling index.\n\n\nCONCLUSIONS\nThis large single center study comparing PP1 adenomas to non-PP1 adenomas did not suggest that these tumors are more aggressive. Further work is warranted to identify pathologic subtypes of pituitary adenomas that are consistently more clinically aggressive.