Aggressive pituitary adenoma and pituitary carcinoma

Anterior pituitary tumours, once considered benign neoplasms, may rarely have aggressive behaviour and can even metastasize. The current guideline of the European Society of Endocrinology defines aggressive pituitary adenomas as radiologically invasive tumours with an unusually rapid growth rate and frequent relapses despite the optimal use of standard therapies. Currently, there is not any single, well-defined pathological marker of malignancy. Pituitary carcinomas are thus clinically defined by the presence of craniospinal or distant metastases, typically developing several years after the first presentation. Histopathology may predict aggressive behaviour if the Ki67 index and mitotic rate are elevated and in case of positive p53 staining. These patients' short- and long-term therapy should be individualized and regularly discussed by a multidisciplinary pituitary team. Besides standard medical treatment administered in maximally tolerated doses, current recommendations suggest repeated surgery and radiotherapy. If this approach fails, the next choice of treatment is chemotherapy with temozolomide. After that, immune checkpoint inhibitors, bevacizumab, and peptide receptor radiotherapy are emerging therapies that should be used on a case-by-case basis.