Prolactinoma overview On the Web
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A prolactinoma is a benign tumor (adenoma) of the pituitary gland that produces prolactin. It is the most common type of pituitary tumor. Symptoms of prolactinoma are caused either by hyperprolactinemia or by pressure of the tumor on surrounding tissues. In women, these adenomas are often small (<10 mm). In either sex, however, they can become large enough to enlarge the sella turcica. These adenomas represent the most common hormone-producing pituitary tumors and account for 45% of all pituitary tumors. MRI is the most sensitive diagnostic test for detecting pituitary tumors (including prolactinoma). Medical therapy for prolactinoma includes dopamine agonists. Surgery is indicated in patients if medical therapy cannot be tolerated. Transsphenoidal resection of the tumor is rarely done among patients with prolactinoma as most of the patients respond to medical management.
In 1970, prolactin was discovered in humans by sensitive bioassay. In 1978, V C Medvei, the President of the Section of History of Medicine (1986-87) of the Royal Society of Medicine in London, wrote in his paper that Queen Mary I of England was believed to have prolactinoma.
Prolactinoma can be classified based either on size or local invasion. Based on size, a prolactinoma can be classified as a microprolactinoma (<10 mm diameter) or macroprolactinoma (>10 mm diameter).
Prolactinoma is the most common type of pituitary adenoma. Prolactinoma may occur in approximately 30% of multiple endocrine neoplasia type 1 patients. It may also occur with Carney complex or McCune-Albright syndrome. There are a few reports of familial cases of prolactinoma unrelated to MEN 1 syndrome. Prolactinoma is also associated with various familial syndromes. On gross pathology, prolactinoma is divided on the basis of size into microprolactinoma and macroprolactinoma. On histological analysis, prolactinoma may be divided into sparsely granulated and densely granulated prolactinomas.
There are no established causes for prolactinoma. Most cases of prolactinoma are sporadic. Prolactinoma may occur in approximately 30% of multiple endocrine neoplasia type 1 patients. It may also occur with Carney complex or McCune-Albright syndrome.
Differentiating prolactinoma from other diseases
Prolactinoma must be differentiated from other causes of hyperprolactinemia that may also present as galactorrhea, amenorrhea, (in females) and infertility (in both males and females). Causes of hyperprolactinemia can be categorized as physiological, pathological, and medication-induced.
Epidemiology and Demographics
45% of pituitary adenomas are prolactinomas, making it the most common type of all pituitary adenomas. Worldwide, the prevalence of sporadic prolactinoma is 6 to 10 per 100,000 persons. The prevalence of prolactinoma in people less than 20 years old is 10 per 100,000 individuals worldwide. Prolactinoma most commonly affects women in reproductive age group (20 to 50 years). Prolactinoma is more common in females than males in people between 20 and 50 years old. Frequency becomes similar after age 50.
There are no established risk factors for prolactinoma. Some conditions increase the risk of prolactinoma, such as multiple endocrine neoplasia type 1 (MEN 1), Carney complex, McCune-Albright syndrome, familial isolated pituitary adenoma, and MEN 1 like syndrome.
Natural History, Complications and Prognosis
If left untreated, 95% of cases of prolactinoma will not show any signs of growth during the first 4 to 6 years. Complications of prolactinoma include pituitary apoplexy and vision loss. Prognosis is generally excellent for cases of microprolactinoma.
History and Symptoms
Common symptoms of prolactinoma include headache, vision changes, decreased libido, infertility, and osteoporosis. In women, common symptoms of prolactinoma include breast tenderness, galactorrhea, and amenorrhea or oligomenorrhea.
Medical therapy for prolactinoma includes dopamine agonists (either cabergoline or bromocriptine). The goal of treatment is to return prolactin secretion to normal, reduce tumor size, correct any visual abnormalities, and restore normal pituitary function.