How many types of pituitary tumors are there?

Too many: Any of the cell types in pituitary may give rise to a tumor. Some make hormone some do not, however all are serious.

2 groups: The are essentially 2 groups of pituitary tumors, both of which are benign. Functioning pit tumors oversecrete one hormone such as acth (cortisol), growth hormone, or prolactin are the common ones. The majority of pit tumors are non-functioning and don't secrete any hormones but cause symptoms because of their size. Your endocrinologist can disting them.