Luteinizing hormone-producing adenoma

Human disease

Pituitary adenoma
[[File:|250px|alt=|Visual field loss in bitemporal hemianopsia: peripheral vision loss affecting both eyes, resulting from a tumor-typically a pituitary adenoma- putting pressure on the optic chiasm.]]
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Field	Oncology, endocrinology
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It is a type of pituitary adenoma of the anterior lobe of the pituitary gland that produces luteinizing hormone (LH).

Pituitary adenomas

Pituitary adenomas are the most common central nervous system tumors, accounting for 10% of all intracerebral tumors and are common in the general population with an incidence of 16.7%, based on a combination of imaging studies and post-mortem examination.

Incidences of silent pituitary adenomas

Clinical presentation

Clinical detection of symptomatic pituitary adenomas typically occurs due to mass effect or hyper secretion of hormones from the anterior pituitary axis.

Symptomatic adenomas

The mass effect is most common in pituitary macroadenomas and results in headaches, visual deficit due to pressure on the optic chiasm, or (rarely) cavernous sinus thrombosis. Pituitary apoplexy is a rare complication caused by hemorrhagic infarction of macroadenomas. It presents with sudden onset of headache, nausea, vomiting, vision loss, and cranial nerve deficits. The risk of this complication in pituitary macroadenomas is 0.4 to 7% over 2-6 years of follow-up.

Hormone producing adenomas

Hypersecretion, or hyposecretion of hormones in the anterior pituitary gland, may occur in micro- or macroadenomas. The most common hypersecretion syndrome is prolactinemia, which produces weight gain, infertility, galactorrhea, hypogonadism, decreased libido, and eventual osteopenia. In women, it also causes amenorrhea. Pituitary adenomas account for 80% of Cushing’s syndrome cases due to hypersecretion of ACTH. Hypersecretion of growth hormone causing acromegaly, and thyrotropin leading to hyperthyroidism, are other less common complications of anterior pituitary hypersecretion. It is noteworthy that surveillance for these complications is relatively straightforward, involving periodic lab tests that are readily accessible in the United States.

Pituitary gland representation

Asymptomatic

Asymptomatic pituitary adenomas are frequently discovered incidental to imaging studies for other medical workups. Frequently referred to as incidentalomas, they have a low complication rate. In one small study, visual field deficits were found in 4.2% and prolactin secretion in 11.9% of incidentalomas.

Progression

Progression in size was seen in 3.2% of microadenomas versus 26.3% of macroadenomas. In a recent metaanalysis by the Mayo Clinic in 2011, microadenoma growth occurred in 3.3 per 100 patient years versus 12.5 per 100 patient years in macroadenomas. The overall incidence of new endocrine dysfunction was 2.4 per 100 patient years.

Treatment

Treatment and surveillance in pituitary adenomas vary according to the size, growth, and hormone production of the tumor. Surgical excision via the transphenoidal route is the most common method of intervention in symptomatic or rapidly growing pituitary adenomas. Other modalities include radiotherapy or medications specific to the cell type. Bromocriptine, for example, is a dopamine agonist used for medical treatment in prolactin-secreting tumors.

Conservative treatment

In the case of non-secreting, asymptomatic, stable pituitary microadenomas, conservative treatment is standard. Initial workup includes a comprehensive history and physical exam focusing on neurological, ophthalmological, and potential stigmata of pituitary hypersecretion.

Labs

Laboratory studies should be obtained to include CBC, electrolytes, kidney and liver functions, thyroid panel, urine cortisol, prolactin level, insulin-like growth factor, follicle stimulating hormone, and luteinizing hormone.

Imaging

Imaging by MRI (if not already performed) is used to assess adenoma size and to look for impending mass effect.

Follow up

Follow-up in a conservatively managed patient typically occurs every 12 months. Education of the patient with respect to possible symptoms from a progressing pituitary adenoma is key to this approach. Presence of symptoms warrants timely follow-up. Annual MRIs are indicated to assess potential tumor growth.

External links

• Cancer.gov: pituitary tumors

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