Pituitary adenoma can be broken down - “adeno” refers to a gland and “oma” refers to a tumor, so pituitary adenoma is a tumor that develops in the hormone-producing cells of the pituitary gland.
Normally, the pituitary is a pea-sized gland, hanging by a stalk from the base of the brain.
It sits just behind the eyes near the optic chiasm, which is where the optic nerves cross.
The anterior pituitary, which is the front of the pituitary gland, contains a few different types of cells, each of which secretes a different hormone.
The largest group of cells are the somatotropes which secrete growth hormone, or GH for short, which goes on to promote tissue and organ growth.
The second largest cell group are the corticotrophs which secrete adrenocorticotropic hormone, or ACTH for short.
ACTH stimulates the adrenal glands to secrete cortisol, a hormone that controls the stress response and metabolic regulation.
A smaller cell group are the lactotrophs which secrete prolactin.
Prolactin stimulates breast milk production, and also inhibits ovulation, which is when an egg cell is released from the ovary, and inhibits spermatogenesis, which is the development of sperm cells.
There are also thyrotrophs which are cells that secrete thyroid stimulating hormone, or TSH which goes on to stimulate the thyroid gland.
And finally, there are also gonadotrophs which secrete two gonadotropic hormones - luteinizing hormone, or LH, and follicle-stimulating hormone, or FSH, both of which go on to stimulate the ovaries or testes.
In pituitary adenomas, one of these cells mutates and becomes neoplastic, meaning that it starts dividing uncontrollably and over time it forms a tumor.