Approximately 10 to 15 percent of pituitary tumors make a hormone called adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to generate proteins known as glucocorticoids. When the body makes too much ACTH, it causes a disorder known as Cushing's disease (also called Cushing’s syndrome). Women in their 30s and 40s are most commonly diagnosed with this disorder.
If you have an ACTH-producing tumor (Cushing’s disease), you may experience one or more of the following signs or symptoms:
- unexplained weight gain
- increased blood pressure
- easy bruising
- moodiness or depression
- irregular or absent menstrual periods
A number of diseases can increase the production of hormones from the adrenal glands. Before beginning treatment, your Memorial Sloan-Kettering team will perform tests to rule out other conditions that could be causing your symptoms.
Cushing's disease is diagnosed using blood tests that look for abnormal amounts of cortisol. This hormone, which is released by the adrenal cortex, aids in metabolism and helps the body recover from physical stress due to surgery, injury, and infection.
Your doctor may perform a high-resolution MRI scan of the brain’s sella, where the pituitary gland is located. (The scan is done after injection of a dye, also called a contrast). Images are obtained at high speed several times after the dye is injected. This ensures the best resolution and visualization of the tumor and the normal gland.)
Sometimes the tumor causing the illness is so small that it is not visible even with these measures. In such cases, or if the diagnosis is uncertain, we use a test called petrosal venous sampling. During this procedure, a blood sample is taken from the petrosal sinuses (the channels that drain the pituitary gland on both sides of the skull) and from blood in your circulatory system (peripheral blood) through an IV.
The levels of ACTH hormone in both samples are compared. Patients with Cushing’s disease due to a tumor in the pituitary gland will exhibit elevated levels of ACTH in the petrosal sample when compared to peripheral blood.
Elevated ACTH levels (Cushing’s disease) could also originate from other tumors located in the lung or elsewhere in the body. In these cases, petrosal sampling would show that ACTH levels do not differ much from the levels obtained from the peripheral blood.
The primary treatment for Cushing’s disease is surgery to remove the tumor.
Memorial Sloan-Kettering surgeons are experienced in using a minimally invasive technique called transnasal transsphenoidal resection to remove pituitary tumors. Using this approach, surgeons are able to bypass brain tissue, operating instead through an incision inside the nasal passage. The risk for neurologic complications with this technique is very low, and the surgery leaves no visible scar.
If the tumor is too large to be removed by minimally invasive surgery, it may be necessary to perform a different type of operation called a craniotomy, in which the tumor is removed through an incision made in the front of the skull.
Radiation therapy may also be used to treat your tumor. One form of external radiation therapy that we use to treat Cushing’s disease is stereotactic radiosurgery, in which special equipment is used to give a single large dose of radiation to a tumor. Intensity-modulated radiation therapy, in which special equipment delivers highly targeted doses of radiation, is sometimes used as well.
However, Cushing’s disease may be difficult to cure completely. Sometimes surgery has to be repeated if the tumor was not completely removed. The tumors can be very small and not readily seen on MRI. Similarly, when the tumor is large, it is unlikely that surgery will cure the tumor, as it may have already spread. Although it is rarely used as a primary treatment, medications can assist in controlling Cushing’s disease.