ESR1 and neoplasm: The tumor specimens obtained after transsphenoidal intervention were histologically and immunohistochemically examined for the following parameters: anterior pituitary hormones, the ki-67 labeling index, CAM 5.2 expression, ER ∝ expression, and somatostatin receptors, which revealed a densely granulated tumor with intense positivity for PRL and ER ∝ , a ki-67 labeling index of 6% and negative MGMT expression.