2025 Poster Presentations
P252: CLINICAL CHARACTERISTICS AND POSTOPERATIVE OUTCOMES IN A LARGE COHORT OF PATIENTS WITH PROLACTIN COSTAINING SOMATOTROPH TUMORS
Kaasinath P Balagurunath, BA1; Christopher S Hong, MD1; Jakob V Gerstl, MBBS1; Ryan Chrenek, MD1; Sean Lyne, MD1; Noah L Nawabi, BS1; Rania A Mekary2; Timothy R Smith, MD, PhD1; 1Brigham and Women's Hospital; 2School of Pharmacy, Massachusetts College of Pharmacy and Health Sciences (MCPHS) University
Introduction: Acromegaly is caused by lesions which are primarily growth hormone (GH) secreting, however a subset of tumors also stain positive for prolactin (PRL). Although previous studies have examined the incidence and histological characteristics of these lesions, little has been documented regarding the clinical/endocrinological characteristics and postoperative outcomes after transsphenoidal surgery (TSS).
Objectives: In this preliminary study, we examined the clinical characteristics and postoperative outcomes in acromegaly patients with PRL positive lesions.
Methods: In this single institution, retrospective study, a large cohort of 156 acromegaly patients who had GH and PRL staining data available between 2008-2024 were examined. Radiological, surgical, clinical, and endocrinological characteristics at baseline and postoperatively were tracked. Pituitary adenoma size, location, and dimensions were determined using preoperative magnetic-resonance-imaging (MRI) and computerized-tomography (CT) imaging. T tests and chi-square tests were not performed due to the high type-1 error rate. A multivariate logistic regression model was created to determine whether PRL co-staining was predictive of postoperative complications, biochemical remission, or recurrence.
Results: Among the 156 patients with staining data available, 95 (60.9%) demonstrated PRL immunopositivity. The most common preoperative symptoms on presentation were headache (42.1% vs 39.3% in PRL+ vs PRL- patients respectively), acromegalic-bone changes (72.6% vs 78.7%), and tumor induced visual loss (21.1% vs 19.7% respectively). Preoperative demographics, as well as the rates of preoperative comorbidities and medication prescription were largely similar between groups.
Preoperatively, GH hypersecretion occurred in 84.8% of PRL+ and 83.3% of PRL- lesions. Unsurprisingly, rates of preoperative hyperprolactinemia were higher in the PRL+ group (26.4% vs 8.8% respectively). Hypogonadism and hypocortisolism were common in both groups (17.9% and 12.8% respectively, overall). Postoperatively, rates of GH hypersecretion were similar between groups (29.6% vs 26.2% in PRL+ vs PRL- respectively). Rates of hypoadrenalism were higher in the PRL+ group (116.3% vs 5.1%), and no other significant differences in postoperative endocrine dysfunction were noted.
Interestingly, rates of tumor adherence and parasellar location were higher in the PRL- group (16.4% vs 5.3%, and 9.1% vs 0% respectively). PRL+ lesions had higher MIB index scores (2.74 ± 2.4 vs 1.6 ± 0.9 respectively) and experienced higher rates of cystic features (20.2% vs 9.3%). Furthermore, the rates of p53, ACTH, and FSH immunopositivity were higher in the PRL+ group (68.7% vs 35.6%, 31.6% vs 13.1%, and 10.5% vs 1.7% respectively). All but two patients received endoscopic TSS, with nasal packing and fat grafting being the most common Sellar reconstruction methods used. Postoperatively, the rates of gross total resection (84.2% vs 83.6%), biochemical remission (75.4% vs 75.5%), and recurrence (11.6% vs 6.6%) were largely similar.
Multivariate logistic regression demonstrated that PRL immunopositivity was not associated with a significantly increased risk of developing surgical complications (dysnatremia or CSF leak), a failure to achieve biochemical remission, or recurrence when adjusted for covariates.
Conclusion: Overall, despite distinct preoperative endocrinological and histological landscapes, PRL immunopositivity in acromegaly patients was not associated with worse postoperative outcomes. In the future, we aim to perform double staining to further classify PRL+ lesions as monomorphic or dimorphic lesions.
