The different types of pituitary cysts are Rathke's cleft cysts, pars intermedia cysts, and arachnoid cysts. Epidermoid cysts and dermoid cysts are also classified as pituitary cysts. A pituitary cyst is defined as a cyst affecting the pituitary gland. These cysts are differentiated by their cellular makeup and their location in the brain.
The Rathke's cleft cyst is the most common type of pituitary cyst. As the pituitary gland develops in a fetus, complications can occur. Normal development occurs when the pituitary gland splits into the anterior and posterior pituitary. This creates a natural cleft formation in the gland. Sometimes, however, the cleft fails to fully regress, and the area fills with fluid. This fluid forms the Rathke's cleft cyst.
Arachnoid cysts are another type of pituitary cyst. These cysts can occur anywhere between the spinal cord and the arachnoid membrane, which is a membrane that protects the brain and spinal cord. They can and do affect the pituitary gland, though not always. They are filled with cerebrospinal fluid that is enclosed in a thin layer of skin and collagen. As the cysts accumulate fluid, they can grow and affect normal brain function.
Pars intermedia cysts include any pituitary cyst that develops on the pars intermedia region of the pituitary gland. The pars intermedia refers to the cleft that normally develops, separating the anterior and posterior pituitary. Rathke's cleft cysts are a type of pars intermedia cyst.
Epidermoid cysts are another kind of pituitary cyst. They grow from epithelial cells, where the arachnoid membrane extends between the two temporal lobes. They are generally harmless and grow slowly along the crevices at the base of the brain. These cysts are commonly referred to as pearly tumors due to their shiny, white coloring when removed during surgery.
Dermoid cysts are one of the most threatening types of pituitary cysts. These cysts stand apart because they tend to be heterogeneous, containing many different types of cells within them. It is common for these types of cysts to contain fatty components and even matted hair. When this type of pituitary cyst bursts and leaks fluid, it can cause serious illness, including meningitis.
It is fairly common for a pituitary cyst not to produce any symptoms. When symptoms do occur, they are usually caused by the cyst's growth, putting pressure on the brain and surrounding nerves and glands. Headaches are a common symptom, but there is no headache specific to pituitary cysts, so it may not be immediately apparent that a cyst is to blame. The pituitary gland is located close to the optic chiasm, so the cyst can affect peripheral vision.