What causes a prolactinoma to be aggressive or to become a pituitary carcinoma?

Introduction: Malignant prolactinoma is an exceedingly rare endocrine tumor and cannot be diagnosed on histological grounds alone. Similarly to other neuroendocrine tumors such as pheochromocytoma, the mitoses index, Ki-67, p53, and others are utilized in helping understand whether a tumor is benign or malignant or to better predict tumor behavior. We here present the unusual case of an unfortunate young man with an aggressive prolactinoma, the complications of which led to his premature death.