Impact of pituitary adenoma histological subtype on remission and disease control in acromegaly

INTRODUCTION: Acromegaly results from different histological subtypes of pituitary adenomas, mainly pure GH-secreting adenomas (densely or sparsely granulated) and GH-PRL adenomas. Data on the impact of histological subtype on surgical outcomes in acromegaly remain limited. OBJECTIVES: This study aimed to assess the impact of pituitary adenoma histological subtype on acromegaly remission at 3 months and last follow-up, as well as on disease control. METHODS: We conducted a retrospective, single-center study of 128 patients who underwent surgery for GH or GH-PRL adenomas, without prior medical therapy, between 2012 and 2022. RESULTS: Among the adenomas, 61% were pure GH (39% DG, 22% SG) and 39% were GH-PRL. Compared to DG adenomas, SG adenomas were diagnosed at a younger age (p = 0.006), were larger (p = 0.022), expressed more SST5 (p = 0.032) and less SST2 (p < 0.001). GH-PRL adenomas were more frequently p53-positive (p = 0.024), had a higher mitotic count (p = 0.017) than DG adenomas and expressed more SST2 than SG adenomas (p < 0.001). The remission rates for DG, GH-PRL and SG adenomas were not significantly different at 3 months (60%, 58% and 43%, p = 0.337), or at last follow-up (80%, 74% and 57%, p = 0.091), nor was disease control at last follow-up (94%, 96% and 82%, p = 0.115) after 42 months. CONCLUSION: Histological subtype was not significantly associated with remission or control of acromegaly. Although a trend toward lower remission rates was observed in SG adenomas, its clinical impact appears limited.