CD34 and pituitary gland adenoma: Some studies have found that several crucial biomarkers of angiogenesis, including VEGF and CD34, were widely expressed in pituitary adenoma [12, 13]; however, other studies have indicated that compared with the normal pituitary gland tissue, pituitary adenoma had lower angiogenesis and CD34/CD105 microvessel density (MVD) [14–17].