The pituitary gland is the most important gland in the body. It produces hormones which control all of the other glands in the body. Pituitary adenomas are tiny lumps which grow within the pituitary gland. These can cause problems by producing extra hormones, for example growth hormone resulting in acromegaly, by preventing the normal production of other pituitary hormones, or by squashing other important structures near the pituitary gland, such as the eye nerves. Almost all pituitary tumours are benign, these are called adenomas. This means that they are not cancerous, and do not spread. Most of the time pituitary adenomas grow slowly and it takes years before they get diagnosed. Pituitary adenomas grow for usually 2-10 years before they get diagnosed.
The vast majority of pituitary adenomas occur spontaneously which means that they are not inherited. However, a small group of patients with pituitary adenomas also have family members with similar disease. If no other hormone abnormality is present the patients has Familial Isolated Pituitary Adenoma or FIPA. Familial pituitary adenomas due to FIPA, MEN1 or Carney complex together account for about 5% of patients with pituitary adenomas.
Pituitary adenomas are normally described as benign which means that they are non-cancerous growths affecting the gland. Only a small number of pituitary adenomas are cancerous. Pituitary adenomas can, however, interrupt the normal functioning of the pituitary gland and this can have serious implications for the health of the patient. The role of the pituitary gland is to produce hormones and these adenomas can cause the gland to produce these hormones in excessive amounts. The position of the adenomas can impact on the type of hormone being released and this is normally how these tumours are classified. The most common types of pituitary adenomas are listed below.
The anterior part of the pituitary gland has 5 different cell types and adenomas can develop from each of the cells types: growth hormone cells, prolactin cells, ACTH cells, LH & FSH cells and TSH cells (Figure 1).
Adenomas developing from growth hormone-secreting cells cause acromegaly or acromegalic gigantism (if they start in childhood). Symptoms of acromegaly include headache, sweating, increased shoe and hand size (Figure 2), increased spacing of teeth (Figure 3), enlarged tongue (Figure 4) change in facial appearence, visual field defects, symptoms of carpal tunnel syndrome (pain, numbness, loss of feeling, clumsiness in the hand), excessive snooring and sleep apnoe, hypertension, diabetes, joint problems and others (Figure 5, click on the picture to see an enlarged version).
Familial acromegaly is one of the most common forms of familial isolated pituitary adenoma. About half of the families have an AIP mutation causing the disease, while the gene causing the disease is not known in the other half. Interestingly several patients with a childhood or young adult-onset acromegaly have been found to have a mutation in the AIP gene, but they do not know of any family history of this disease. These patients may have other family members who also carry the gene abnormality and are therefore predisposed (have a chance) to develop pituitary adenoma.
Please read further about specific symptoms, diagnosis and therapy of acromegaly on the following websites:
Adenomas developing from prolactin cells are called prolactinomas. Small prolactinomas are more common in women (called microprolactinomas) while men have prolactinomas rarely but they are usually larger (macroprolactinomas). Prolactinomas often cause disturbance of the periods in women and problems with erections in men. Sometimes a milky fluid can appear to be released from the breast. Prolactinomas often respond very well to medical therapy with bromocriptine or cabergoline. Familial prolactinomas seen commonly in FIPA families. Sometimes other family members have acromegaly, in these cases AIP mutations are common, while in families where only prolactinomas occur do not have AIP mutations. The gene causing 'pure prolactinoma' families is currently unknown. Not all patients with high prolactin levels will have a prolactinoma, drugs and other types of pituitary lesions can also elevate prolactin levels. Please read further about specific symptoms, diagnosis and therapy of prolactinomas on the following websites:
Adenomas developing from LH & FSH cells most often not actually secrete any hormones or only in very minimal amounts and clinically are considered as non-functioning adenomas (NFPAs). Please read further about specific symptoms, diagnosis and therapy of NFPAs on the following websites:
Adenomas developing from ACTH-secreting cells are called corticotrophinomas or Cushing's disease. Please read further about specific symptoms, diagnosis and therapy of Cushing's disease on the following websites:
Very rarely TSH-secreting cells can develop adenomas called TSHoma. In this case the patient will have symptoms of high thyroid hormone level. Please read further about specific symptoms, diagnosis and therapy of Cushing's disease on the following websites:
A special pituitary adenoma type is the so called craniopharyngioma, which develops from pituitary cells of an early developmental stage. These adenomas usually do not secrete any hormones. It is a rare disease occurring in children or at late middle age. Please read further about specific symptoms, diagnosis and therapy of craniopharyngioma on the following websites:
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