Are prolactinomas ever malignant?
Malignant prolactinomas account for about 1 to 2 per 1000 pituitary adenomas. Features that may suggest malignancy are loss of responsivity to dopamine agonists in a previously responsive tumor, rapid regrowth after surgery, repeated operations for tumor growth and rising prolactin levels, the development of metastases, and high Ki-67 labeling. Aside from surgery, other treatment measures that may be effective are radiation therapy and/or temozolomide, an alkylating agent that depletes a DNA repair enzyme.
