Pituitary tumors are unusual growths that develop in the pituitary gland. This gland is an organ about the size of a pea. It's located behind the nose at the base of the brain. Some of these tumors cause the pituitary gland to make too much of certain hormones that control important body functions. Others can cause the pituitary gland to make too little of those hormones.

Most pituitary tumors are benign. That means they are not cancer. Another name for these noncancerous tumors is pituitary adenomas. Most adenomas stay in the pituitary gland or in the tissue around it, and they grow slowly. They typically don't spread to other parts of the body.

Scientists aren’t sure of the exact cause of pituitary adenomas.

But some adenomas have been linked to accidental changes, or mutations in DNA, the material within a cell that makes up our genes. These changes cause the cells in your pituitary gland to grow out of control, making a mass (growth). The genetic changes can be passed down from parents to children (inherited), but they usually happen randomly.

Pituitary adenomas are also associated with certain genetic conditions, including:

• Multiple endocrine neoplasia type 1.

• Multiple endocrine neoplasia type 4.

• Carney complex.

• X-LAG syndrome.

• Succinate dehydrogenase-related familial pituitary adenoma.

• Neurofibromatosis type 1.

• Von Hippel–Lindau syndrome.

Having one of these conditions makes it more likely that you’ll develop a pituitary adenoma, but you can still have an adenoma without having one of these conditions.