One for the money, two for the show, three to make ready....

Just how many kinds of tumors are there associated with Cushing's? Wait, are we talking about pituitary tumors? Or adrenal tumors? How about ectopic tumors? Are you beginning to get the picture of why this illness is so hard to diagnose?

PITUITARY TUMORS/ADENOMAS:

So, let's talk about tumors. These are also sometimes called adenomas. Pituitary adenomas are classified several ways. They may be classified by pathology, by size, and by hormone production. I'm going to keep it simple here and list the basic types of tumors by the hormones they produce. Bear in mind that many pituitary adenomas produce more than one hormone. This production is not held in check by the body's normal feedback loops, thus they aren't controlled.

• Corticotroph (ACTH-Producing) Adenomas :
  The corticotroph adenoma secretes adrenocorticotropic hormone (ACTH), which results in Cushing Disease because it stimulates the adrenal glands to overproduce cortisol. These tumors are initially confined to the sella turcica, but they may enlarge and become invasive especially after bilateral adrenalectomy. This is called Nelson's Syndrome.
  
• Somatotroph (GH-Producing) Adenomas:
  Somatotroph adenomas produce growth hormone (GH), resulting in gigantism in younger patients and acromegaly in adults. These tumors may also extend beyond the sella.
  
• Thyrotroph (TSH-Producing) Adenomas:
  Thyrotroph adenomas secrete thyroid-stimulating hormone (TSH), also known as thyrotropin, which results in hyperthyroidism without TSH suppression. Many are large and invasive and typically have other types of adenoma cells included, such as ACTH and/or GH.
  
• Lactotroph (PRL-Producing) Adenomas:
  Lactotroph adenomas secrete prolactin (PRL) and are typically an intrasellar tumor. However, they can become large enough to enlarge the sella turcica.
  
• Nonfunctioning (Endocrine-Inactive) Adenomas:
  These tumors cause symptoms when they extend beyond the sella, which results in pressure on the surrounding structures such as optic nerves and carotid veins. They are not associated with clinical and biochemical evidence of hormone excess.
  
• Carcinomas:
  Pituitary carcinomas, although extremely rare, are usually endocrinologically functional, and ACTH-producing and PRL-producing tumors are the most frequent.
  
• Other Tumors:
  Other tumors of the pituitary include craniopharyngiomas, meningiomas, and germ cell tumors. Even rarer are the granular cell tumors, pituicytomas, and gangliogliomas. Most rare include gangliocytomas, lymphomas, astrocytomas, and ependymomas.

ADRENAL TUMORS/ADENOMAS:

When a tumor in an adrenal gland overproduces hormones, the tumor is called a functioning tumor. A tumor in an adrenal gland that does not produce hormones is, understandably, called a nonfunctioning tumor. A tumor can start in an adrenal gland (called a primary adrenal tumor) or it can begin in another organ, such as the lungs, and then metastasize (spread) to the adrenal glands. I'm going to focus on primary adrenal gland tumors.

• Adenoma:
  An adenoma is a benign nonfunctioning tumor of the adrenal cortex. Also called an adrenocortical adenoma, this tumor usually does not cause symptoms, and, if it is small, may not require any treatment. However, as it grows it can put pressure on parts of the gland causing it to under or overproduce hormones. The cause of adrenal adenomas is unknown, but the current accepted theory is that they arise because of mutations in certain genes. Adrenal adenomas are more common in some inherited diseases, including multiple endocrine neoplasia type I, Beckwith-Wiedemann syndrome and the Carney complex.
  
  Chronic adrenal stimulation by ACTH leads to bilateral adrenocortical hyperplasia and, if long-standing, nodular transformation according to recent research. Thus, an ACTH producing tumor of the pituitary or ectopic tumor may stimulate the adrenals to form tumors or become hyperplastic (more about hyperplasia in a bit).
  
• Adrenocortical carcinoma:
  Although exceedingly rare this is the most common type of malignant adrenal gland tumor, affecting the cortex, also called an adrenal cortical carcinoma. Adrenocortical carcinoma can be a functioning or nonfunctioning tumor. If the tumor is functioning, it may produce more than one hormone.
  
• Pheochromocytoma:
  A pheochromocytoma is a rare tumor that develops in the core of an adrenal gland. It secretes excessive amounts of catecholamines, usually epinephrine and norepinephrine.
  
• Neuroblastoma:
  Neuroblastoma is a disease in which malignant cells form in nerve tissue of the adrenal gland. It is very rare.

If that isn't enough, there is another form of tumor that isn't a tumor. It's called hyperplasia. These tumor cells may invade the pituitary or the adrenals in nests throughout the gland. Rather than go in-depth right now, I'll post some links to articles so you can explore the topic:

Pituitary Hyperplasia: A Review
Adrenal Hyperplasia

This is just a basic, no-frills outline of various tumors/adenomas associated with Cushing's Disease. And now....four to go.....to bed, that is....