Pituitary adenoma overview

Pituitary adenoma Microchapters
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Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Pituitary adenoma from other Diseases
Epidemiology and Demographics
Risk Factors
Natural history, Complications and Prognosis
Diagnosis
Staging
History and Symptoms
Physical Examination
Laboratory Findings
CT
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ahmad Al Maradni, M.D. [2]

Overview

Pituitary adenomas are tumors that occur in the pituitary gland, and account for about 10% of intracranial neoplasms. They often remain undiagnosed, and small pituitary tumors are found in 6 to 24 percent of adults at autopsy. Pituitary adenomas arise within the anterior lobe (adenohypophysis) of the gland. Pituitary adenoma may be classified according to the size of the adenoma and type of hormone secretion, subtypes include corticotrophic, somatotrophic, thyrotrophic, gonadotrophic, and lactrotrophic adenomas. Adenomas less than 10mm are called microadenomas. There are no established causes for Pituitary adenoma. Patients with pituitary adenoma may progress to develop lethargy, headache, nausea, and vomiting. Common complications of pituitary adenoma include bitemporal hemianopia , anosmia, acromegaly, gigantism and Cushing's syndrome. Prognosis is generally good, and approximately 18% of patients with macroadenoma require further treatment. Pharmacologic medical therapy is recommended among patients with prolactinoma, thyrotrophic, somatotrophic and adrenocorticotropic adenomas. The transsphenoidal microsugrical approach is the mainstay of treatment for growth hormone-(GH) producing adenomas, adrenocorticotropic hormone-(ACTH) producing adenomas, and macroadenomas.

Historical Perspective

Pituitary adenoma was first described by Pierre Marie, a French neurologist In 1886.

Classification

Pituitary adenoma may be classified according to the size of the adenoma and type of hormone secretion, subtypes include corticotrophic, somatotrophic, thyrotrophic, gonadotrophic, and lactrotrophic adenomas.

Pathophysiology

On gross pathology, a well circumscribed suprasellar mass is a characteristic finding of pituitary adenoma. On microscopic histopathological analysis, a monomorphic expansion of usually one cell type with lack of reticulin network among neoplastic cells is a characteristic finding of pituitary adenoma.

Causes

There are no established causes for Pituitary adenoma.

Differential Diagnosis

Pituitary adenoma must be differentiated from other diseases such as craniopharyngioma, meningioma, arachnoid cyst, and pituitary carcinoma.

Epidemiology and Demographics

In the USA, the incidence pituitary adenoma is approximately 3.12 per 100,000 individuals. The prevalence of pituitary adenoma is approximately 100 per 100,000 individuals worldwide.

Risk Factors

The most potent risk factor in the development of pituitary adenoma is presence of family history of either pituitary tumor, multiple endocrine neoplasia type 1 (MEN1), or McCune-Albright syndrome.

Pituitary adenoma natural history, complications, and prognosis

Patients with pituitary adenoma may progress to develop lethargy, headache, nausea, and vomiting. Common complications of pituitary adenoma include bitemporal hemianopia , anosmia, acromegaly, gigantism and Cushing's syndrome. Prognosis is generally good, and approximately 18% of patients with macroadenoma require further treatment.

Diagnosis

Staging

According to American Joint Committee on Cancer classification and staging system for pituitary tumors there is no staging system available for pituitary adenoma.

History and Symptoms

The hallmark of pituitary adenoma is increased intracranial pressure. A positive history of visual field defect, headache, and menstrual irregularities is suggestive of pituitary adenoma. The most common symptoms of pituitary adenoma include galactorrhea, oligomenorrhea , erectile dysfunction, and loss of libido.

Physical Examination

The presence of altered mental status, nausea, lethargy and visual filed defect (bitemporal hemianopsia) on physical examination is suggestive of pituitary adenoma.

Laboratory Findings

Laboratory findings consistent with the diagnosis of pituitary adenoma include elevated serum prolactin level and elevated or decreased serum levels of other pituitary hormones.

CT

Head CT scan may be helpful in the diagnosis of pituitary adenoma. Findings on CT scan suggestive of pituitary adenoma include a large suprasellar mass that invade surrounding structures, calcification, and rarely hemorrhage.

MRI

On brain MRI, pituitary adenoma is characterized by a large mass with heterogeneous signal. Other findings may include remodeling of the floor of the sella and deviation of the pituitary infundibulum to the opposite side.

Other Imaging Studies

Historically, before the advent of MRI, the pituitary was imaged by lateral skull x-rays to look for remodelling of the pituitary fossa.

Other Diagnostic Studies

Inferior petrosal sinus sampling may be performed to detecthormonally active pituitary microadenoma.

Treatment

Medical Therapy

Pharmacologic medical therapy is recommended among patients with prolactinoma, thyrotrophic, somatotrophic and adrenocorticotropic adenomas.

Surgery

The transsphenoidal microsugrical approach is the mainstay of treatment for growth hormone-(GH) producing adenomas, adrenocorticotropic hormone-(ACTH) producing adenomas, and macroadenomas.

primary Prevention

There are no primary preventive measures available for pituitary adenoma.

Secondary Prevention

Secondary prevention strategies following pituitary adenoma include a regular check up of pituitary hormones serum levels and regular neuro-ophthalmic examination.