Prolactinoma overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Anmol Pitliya, M.B.B.S. M.D.[2], Faizan Sheraz, M.D. [3]
Overview
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.
Historical Perspective
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.
Classification
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).
Pathophysiology
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.
Causes
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.
Risk Factors
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.
Screening
There is insufficient evidence to recommend routine screening for prolactinoma.
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.
Physical Examination
Patients with prolactinoma generally appear healthy. The most common physical examination finding of prolactinoma is visual field defects (bitemporal hemianopsia).
Laboratory Findings
Laboratory findings consistent with the diagnosis of prolactinoma include markedly elevated prolactin levels.
ECG
There are no ECG findings associated with prolactinoma.
X-ray
There are no X-ray findings associated with prolactinoma.
Ultrasound
There are no ultrasound findings associated with prolactinoma.
CT Scan
CT scan of head is usually normal in patient of prolactinoma. Sometimes, enlargement of sella turcica may be found in case of macroprolactinoma.
MRI
MRI may be diagnostic of prolactinoma. Magnetic resonance imaging (MRI) is the most sensitive test for detection of pituitary tumors and determination of their size.
Medical Therapy
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.
Surgery
Surgery is not the first-line treatment option for patients with prolactinoma. Surgery is usually reserved for patients whose medical therapy fails to reduce the size of the tumor.
Primary prevention
There is no established method for primary prevention of prolactinoma.
Secondary prevention
There is no established method for secondary prevention of prolactinoma.
References