Endocrine Abstracts

Background: Despite the benign nature of pituitary adenomas, microscopic examination of surgical specimens showed that dural invasion occurs in about 42-85% of cases. No studies about dura mater invasion were conducted specifically in acromegaly, so the aim of the present study was to evaluate the relationship between histologically verified dural invasion and the “aggressiveness” features of GH-secreting adenomas.

Methods: A prospective study included all consecutive acromegaly patients that underwent neurosurgery (NS) at the Division of Neurosurgery of the University of Turin, between 2017 and 2020. All patients were operated with a 3DHD endoscope using an endoscopic endonasal approach by a single skilled neurosurgeon. For each patient the fallowing data were collected: 1) clinical, biochemical and morphological data at diagnosis, three months and one year after NS; 2) pathological features (dura mater invasion, immunohistochemical analyses, proliferation index Ki67 and p53, granulation pattern; 3) radiological findings at RMI scan, in particular intensity on T2-wighted images.

Results: 35 acromegaly patients enrolled. Eleven patients had dura invasion (31%), while 24 did not have (69%). No significant differences were found in gender and age at diagnosis between INV+ and INV-. No difference was found in IGF-1 levels (INV+: 752 ng/ml, [548-987] ng/ml vs INV-: 664 ng/ml, [394-894] ng/ml) and IGF-1/ULN (2.5, [2.3-3.3] vs 2.4, [1.68 - 3.1]). GH levels at diagnosis were higher in INV+ (84.5 ng/ml, [29-153] ng/ml vs 17.2 ng/ml, [4.4-36] ng/ml, P=0.02). ROC curve analysis for GH levels at diagnosis showed that GH > 27 ng/ml was able to distinguish patients with dura mater invasion (AUC 0.760;P=0.006, sensitivity 80% and specificity 73%) and patients with GH > 27 ng/ml at diagnosis had a 10 times higher risk of dura invasion (Odds ratio 10.7; IC 95% 1.74-65.27). No difference was found in morphological, radiological and pathological features. We also analysed predictive parameters of healing. IGF-1 levels at diagnosis (625.5 ng/ml; [391.5 -867.5] ng/ml vs 872 ng/ml; [812 − 1011.5]ng/ml, P=0.03) and proliferation activity (Ki-67≥3%) were significantly lower in cured patients (16% vs 67%, P=0.03), while disease remission rate at three months was greater (100% vs 44%, P=0.002) compared to persistent disease patients.

Conclusion: The only parameter significantly associated with the dura mater invasion is GH levels at diagnosis. The dura mater invasion does not affect the possibility of recovery from acromegaly at 12 months. We confirmed that lower IGF-1 levels at diagnosis and lower Ki-67 are significantly associated with healing after surgery.