Endocrine Abstracts

Introduction: In the search for markers of invasiveness of pituitary adenomas, we studied the expression of Ki-67 antigen, TOPO 2A (topoisomerase 2 alpha), AIP (Aryl Hydrocarbon Receptor-Interacting Protein), and VEGF (Vascular Endothelial Growth Factor) in somatotropinomas.

Material and methods: We studied retrospectively a group of 31 patients (20 female, 11 male) of mean age 43.3±14.3 years who underwent pituitary tumour surgery. Expression of Ki-67, TOPO 2A, AIP, and VEGF in surgical specimens was determined by immunocytochemistry. Relations between quantitatively determined staining indices and clinical symptoms, tumour features, and MR imaging, were analysed. In all studied adenomas GH expression was confirmed by immunostaining. The mean value of the largest tumour dimensions in MRI, was 22.84±21.23 mm. Local invasiveness, defined as sella turcica destruction, cavernous sinus penetration, optic chiasm compression or suprasellar propagation, was observed in 18/31 patients (58.1%).

Results: In our somatotropinoma samples, Ki-67 was expressed in 77.4%, TOPO 2a in 87.1%, AIP in 83.8%, and VEGF in 87.1% of 31 cases. The median values of Ki-67, TOPO 2a, AIP, and cytoplasmic VEGF indices were 1.23% (IQR=2.17), 1.5% (IQR=1.6), 21.16% (IQR=19.76) and 16.64% (IQR=16.41) respectively. Ki-67, TOPO 2a, AIP, and VEGF indices did not correlate with patient age nor gender (P>0.05). Values of Ki-67 and of TOPO 2A indices correlated with tumour size (for Ki-67: r=0.42, P=0.025; for TOPO 2A: r=0.53, P=0.003). No correlation between AIP or VEGF expression with tumour size was found. In invasive, as compared with non-invasive somatotropinomas, significantly higher indices were found only for TOPO 2A (median values: 1.96% (IQR=1.9) vs 1.04% (IQR=1.4), P=0.034).

Conclusions: Ki-67, TOPO 2a, AIP, and VEGF were expressed in over 70% of all somatotropinomas. Only Ki=67 and TOPO 2A expression was related to tumour size. Only TOPO 2A expression was found to correlate with tumour invasiveness.