Cimpean AM, et al. – The purpose of this study was to analyze the involvement in the pathogenesis of pituitary adenomas and to develop the association of the expression with different growth factors and growth factor receptors known to have a prognostic and/or therapeutic role. As evidence accumulates, the outcomes support the presence of two molecular subtypes of FS cells GFAP+/vascular endothelial growth factor (VEGF)+/S100 respectively and another one that is GFAP–/S100+/EGFR+ simultaneously with the classical variant GFAP+/S100+. Moreover, it is possible that S100+/EGFR+ pituitary adenomas represent a group of pituitary adenomas with an aggressive behaviour and a high ability of invasion and recurrence.