Endocrine Abstracts

Introduction: The clinical and biochemical spectrum of pituitary acromegaly is wide and variable. There are pure somatotroph tumors(ST), immunohistochemically positive only for GH, and pluri-hormonal(PL), also positive for other hormones, and they appear to have different presentations and responses to treatment.

Aims: To compare the clinical presentation, imaging characteristics and response to treatment of acromegalic patients according to the pituitary tumour histopathology.

Descriptive statistics: From the 75 patients, 66.7%(n=50) were female with mean age at diagnosis of 48.8±12.7 years. At diagnosis, 79.2%(n=57) had acromegaloid phenotype, 60.9%(n=39) presented with headaches and 39.3%(n=24) suffered from visual impairment. Hypertension (39,2%), diabetes/pre-diabetes (35.1%) and obstructive sleep apnea (24.3%) were the most prevalent comorbidities. Regarding the biochemical profile, 88% patients (n=66) had functioning tumors: 77.3% (n=51) of these producing only GH, 19.7% (n=13) GH plus prolactin and 1 case produced GH plus ACTH. 33.3% patients(n=25) had pituitary hormone deficiencies at diagnosis: hypogonadism being the most common (32.4%). In the MRI, 77.3%(n=58) had a macroadenoma. Postoperative remission (nadir GH<1µg/l) occurred in 29.3%(n=22) and 32% patients(n=24) developed new pituitary insufficiencies, mainly adrenal insufficiency (16%). In the anatomopathological analysis, 64%(n=48) were pure ST and 36% (n=27) were PL.

Results: There were no differences between ST and PL in terms of age (47.5±12.2 vs. 48.9±13.7 years), comorbidities, and pituitary hormone deficiencies at diagnosis or MRI-adenoma dimensions (19±10.3 vs. 25.4±14.4 mm, respectively). However, ST had greater GH levels at diagnosis than PL: 9.9(IQR 22.5) vs. 4.6(IQR 11.8) times above the upper limit of normal(P=0.043). PL were more often non-functioning: 22.2%(n=6) vs. 4.2%(n=2): P=0.045. ST also had greater suprasellar extension(56.3%) than PL(33.3%): P=0.009. PL showed greater sphenoid sinus invasion: 25.9% vs. 6.3% (P=0.03). There was no statistically significant difference in cavernous sinus invasion between ST and PL. Sparsely granulated tumors(SG) tended to show greater compression of the optic chiasm (P=0.05) than densely granulated(DG). There were no statistically significant differences in immediate and long-term post-operative remission and relapse between ST and PT, and between DG and SG. However, DG had better response to medical treatment given after surgery: 61.5% had parcial/complete responses (defined as IGF-1 reduction≥50%/normalization, respectively) vs. 41.7% in sparsely granulated tumors(P=0.03).

Conclusions: In this cohort, PL had lower GH levels at diagnosis, more frequently were non-functioning and more frequently had sphenoid sinus invasion, but this was not reflected on the remission rates. Therefore, PL tumours appear to have different biologic behaviour than ST, but the clinical implications of these findings require further clarification.