HETEROGENEITY OF C ERB B FAMILY MEMBERS EXPRESSION IS RELATED TO CELL MORPHOLOGY AND IMMUNOPROFILE IN PITUITARY ADENOMAS

Abstract

Purpose. Epidermal growth factor receptor (EGFR, HER1) and human epidermal receptor 2 (HER2) assessement in pituitary adenomas related to hormone profile. Design and methods. For 60 retrospective cases of pituitary adenomas, we established the histopathologic diagnosis by using morphological stains, followed by case selection for immunoprofile and EGFR and HER 2 assessement. Results. More than one third of the studied pituitary adenomas (33,33%) were positive for HER2, with membranar pattern in basophilic cells and with predominantly cytoplasmic, granular pattern for acidophils cells. HER2 immuno-expression characterized PRL secreting adenomas (p=0.005) and associations between FSH-LH (p< 0.001) TSH-FSH (p=0,024) and TSH-LH (p=0.028). In situ hybridization confirmed HER2 gene amplification in 33,34% out of all positive cases for HER2 by immunohistochemistry. EGFR positivity was found significantly for GH-prolactin (p=0.000) and prolactin-ACTH (p=0.045) co-expressing pituitary adenomas, peritumoral macrophages and folliculostellate cells. Conclusions. Differential HER2 and EGFR expression related to hormone profile heterogeneity can define different subclasses of pituitary adenomas and could explain clinical, prognostic and therapeutic heterogeneity which are observed in clinical practice. Our results support re-classification of pituitary adenomas based on molecular approach which should include markers with well certified prognostic and therapeutic impact.

Keywords

• HER2
• EGFR
• pituitary adenomas
• targeted therapies.