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.[1] 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 tumor is usually done among patients with prolactinoma.
Historical Perspective
In 1970, Prolactin was discovered in human by sensitive bioassay.[2]
Classification
Prolactinoma can be classified based upon either 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 adenomas. Prolactinoma may occur in approximately 30% of Multiple endocrine neoplasia type 1.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.[1] Prolactinoma is also associated with various familial syndromes.[3] On gross pathology, prolactinoma is divided on the basis of size: microprolactinoma and macroprolactinoma. On microscopic histological analysis, prolactinoma has two types: sparsely granulated variant and densely granulated variant.
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. It may also occur with Carney complex or McCune-Albright syndrome.[1]
Epidemiology and Demographics
45% of pituitary adenoma are prolactinoma, making it the most common of all pituitary adenoma.[1] The prevalence of prolactinoma in age group <20 years is 10 per 100,000 individuals worldwide. Prolactinoma most commomly affects age group 20 to 50 years. Prolactinoma is more common in females than males in age group 20 to 50 years. Frequency becomes similar after age 50 years.
Risk Factors
There are no established risk factors for prolactinoma. Some conditions increases 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.
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.
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 year period. Complications of prolactinoma include pituitary apoplexy, 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. Most common physical examination finding of prolactinoma include visual field defects (bitemporal hemianopsia).
Laboratory Findings
Laboratory findings consistent with the diagnosis of prolactinoma include markedly elevated prolactin levels.
ECG
There is no ECG finding associated with prolactinoma.
X-ray
There is no X-ray finding associated with prolactinoma.
Ultrasound
There is no ultrasound finding associated with prolactinoma.
CT Scan
On CT scan of head, prolactinoma is characterized by enlargement of the pituitary gland.
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.[4]
Surgery
Surgery is not the first-line treatment option for patients with prolactinoma. Surgery is usually reserved for patients in whom 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 primary prevention of prolactinoma.
References
- ↑ 1.0 1.1 1.2 1.3 Ciccarelli A, Daly AF, Beckers A (2005). "The epidemiology of prolactinomas". Pituitary. 8 (1): 3–6. doi:10.1007/s11102-005-5079-0. PMID 16411062.
- ↑ Frantz, Andrew G. (1978). "Prolactin". New England Journal of Medicine. 298 (4): 201–207. doi:10.1056/NEJM197801262980408. ISSN 0028-4793.
- ↑ Karhu A, Aaltonen LA (2007). "Susceptibility to pituitary neoplasia related to MEN-1, CDKN1B and AIP mutations: an update". Hum Mol Genet. 16 Spec No 1: R73–9. doi:10.1093/hmg/ddm036. PMID 17613551.
- ↑ Melmed S, Casanueva FF, Hoffman AR, Kleinberg DL, Montori VM, Schlechte JA; et al. (2011). "Diagnosis and treatment of hyperprolactinemia: an Endocrine Society clinical practice guideline". J Clin Endocrinol Metab. 96 (2): 273–88. doi:10.1210/jc.2010-1692. PMID 21296991.