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Causes, Presentation, And Evaluation of Sellar Masses

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  • 11/27/2014 Causes, presentation, and evaluation of sellar masses

    http://www.uptodate.com/contents/causes-presentation-and-evaluation-of-sellar-masses?topicKey=ENDO%2F6632&elapsedTimeMs=4&view=print&displayedV 1/15

    Official reprint from UpToDate www.uptodate.com 2014 UpToDate

    AuthorPeter J Snyder, MD

    Section EditorDavid S Cooper, MD

    Deputy EditorKathryn A Martin, MD

    Causes, presentation, and evaluation of sellar masses

    All topics are updated as new evidence becomes available and our peer review process is complete.Literature review current through: Oct 2014. | This topic last updated: Jan 14, 2014.

    INTRODUCTION Sellar masses typically present in one or more ways:

    This topic will review the causes, clinical manifestations, and evaluation of sellar masses. The clinical presentation

    and management of individual pituitary tumors and of hypopituitarism are discussed separately. (See appropriate

    topic reviews.)

    CAUSES Pituitary adenomas are the most common cause of sellar masses from the third decade on,

    accounting for up to 10 percent of all intracranial neoplasms [1-3]. Other disorders, which are often difficult to

    distinguish from pituitary adenomas by imaging, include physiologic enlargement of the pituitary and benign and

    malignant tumors (table 1).

    Pituitary adenomas Pituitary adenomas are benign tumors of the anterior pituitary, but they are true

    neoplasms, as shown by clonality studies [4,5].

    Incidence and prevalence There are few population studies of the incidence and prevalence of pituitary

    adenomas. However, a population-based study in Northern Finland, where all patients within a health care district

    are referred to a predetermined medical center, found the following standardized incidence rates per 100,000

    (cases diagnosed between 1992 and 2007) [6]:

    Past studies of pituitary adenomas in the population are thought to have underestimated their true prevalence. In a

    current report from a single community of over 80,000 inhabitants in England, the prevalence of pituitary

    adenomas per 100,000 was fourfold higher than previous estimates [7]:

    Genetics Classic oncogene mutations are rarely found in pituitary adenomas, but mutations in the following

    genes may play a role in the development of one or more types of pituitary adenomas:

    With neurologic symptoms, such as visual impairment or headache

    As an incidental finding on magnetic resonance imaging (MRI) performed for some other reason

    With hormonal abnormalities

    All pituitary adenomas 4.0

    Lactotroph adenomas 2.2

    Clinically nonfunctioning adenomas 1.0

    Somatotroph adenomas 0.34

    Corticotroph adenomas 0.17

    All adenomas 77.6

    Lactotroph adenomas 44.4

    Nonfunctioning adenomas 22.2

    Somatotroph adenomas 8.6

    Corticotroph adenomas 1.2

  • 11/27/2014 Causes, presentation, and evaluation of sellar masses

    http://www.uptodate.com/contents/causes-presentation-and-evaluation-of-sellar-masses?topicKey=ENDO%2F6632&elapsedTimeMs=4&view=print&displayedV 2/15

    Classification Adenomas are classified by size and the cell of origin. Lesions smaller than 1 cm are

    classified as microadenomas, and lesions larger than 1 cm are classified as macroadenomas. The tumors can

    arise from any type of cell of the anterior pituitary and may result in increased secretion of the hormone(s) produced

    by that cell and/or decreased secretion of other hormones due to compression of other cell types [15].

    Pituitary hyperplasia There are several recognized causes of hyperplasia of the pituitary. These may present

    as sellar masses and be misdiagnosed as pituitary adenomas:

    Other benign tumors Several other benign tumors can occur in or near the sella, including

    craniopharyngiomas, meningiomas, and less commonly, pituicytomas.

    Craniopharyngioma Craniopharyngiomas are solid or mixed solid-cystic benign tumors that arise from

    remnants of Rathke's pouch along a line from the nasopharynx to the diencephalon. Most are either intrasellar or

    suprasellar. About 50 percent present clinically during childhood and adolescence, the other 50 percent present

    MEN1 Loss of function mutations of this tumor suppressor gene appear to be responsible for the tumors

    that occur in the parathyroids, pancreatic islets, and pituitary glands of patients who have multiple endocrine

    neoplasia type 1 syndrome [8]. However, mutations in this gene do not appear to cause sporadic pituitary

    adenomas [9]. (See "Multiple endocrine neoplasia type 1: Definition and genetics".)

    Gs-alpha An activating mutation of the alpha subunit of the guanine nucleotide stimulatory protein (Gs-

    alpha) gene is found in approximately 40 percent of somatotroph adenomas [10,11]. These mutations result in

    constitutive activation of adenylyl cyclase, which may play a role in both cell division and excessive growth

    hormone secretion by these adenomas. (See "Causes and clinical manifestations of acromegaly".)

    PTTG The pituitary tumor transforming gene, which was cloned from a rat pituitary tumor cell line, is

    overexpressed in most human pituitary adenomas compared with nonadenomatous pituitary tissue [12,13].

    FGF receptor-4 A truncated form of the receptor for fibroblast growth factor-4 has been identified in human

    pituitary adenomas. Transgenic mice that express this mutation in their lactotroph cells develop lactotroph

    adenomas [14].

    Gonadotroph adenomas usually present as clinically nonfunctioning sellar masses. (See "Clinical

    manifestations and diagnosis of gonadotroph and other clinically nonfunctioning pituitary adenomas".)

    Thyrotroph adenomas may present as clinically nonfunctioning sellar masses that secrete only alpha or TSH-

    B subunits or may cause hyperthyroidism due to increased secretion of intact thyroid stimulating hormone.

    (See "Disorders that cause hyperthyroidism", section on 'TSH-mediated hyperthyroidism'.)

    Corticotroph adenomas usually cause Cushing's disease. (See "Establishing the cause of Cushing's

    syndrome".)

    Lactotroph adenomas usually cause hyperprolactinemia, which leads to hypogonadism in women and men.

    (See "Clinical manifestations and evaluation of hyperprolactinemia".)

    Somatotroph adenomas typically cause acromegaly due to increased growth hormone secretion. (See

    "Causes and clinical manifestations of acromegaly".)

    Lactotroph/somatotroph adenoma combinations that secrete both prolactin and growth hormone [16] are well

    recognized and cause the clinical syndromes of both hormones. Other mixed cell adenomas, sometimes

    called plurihormonal adenomas, can involve any combination of cells, but are uncommon.

    Lactotroph hyperplasia during pregnancy (see "Causes of hyperprolactinemia")

    Thyrotroph and gonadotroph hyperplasia due to long-standing primary hypothyroidism and primary

    hypogonadism, respectively [17-21]

    Somatotroph hyperplasia due to ectopic secretion of growth hormone-releasing hormone [22]

  • 11/27/2014 Causes, presentation, and evaluation of sellar masses

    http://www.uptodate.com/contents/causes-presentation-and-evaluation-of-sellar-masses?topicKey=ENDO%2F6632&elapsedTimeMs=4&view=print&displayedV 3/15

    after age 20, some not until age 70 or 80. The major presenting symptoms are growth retardation in children and

    abnormal vision in adults. In addition, pituitary hormonal deficiencies, including diabetes insipidus, are common.

    (See "Craniopharyngioma".)

    Meningioma A meningioma is a usually benign tumor arising from the meninges anywhere within the head.

    Some arise near the sella, causing visual impairment and hormonal deficiencies. (See "Meningioma: Clinical

    presentation and diagnosis".)

    Pituicytoma This is an uncommon, low-grade (WHO grade 1), indolent glioma arising from the pituicytes of

    the posterior pituitary. It presents as a sellar mass, which is usually mistaken for a pituitary adenoma, and has no

    known hormonal secretory function.

    Malignant tumors Some malignant tumors arise within or near the sella, and others metastasize to this site.

    Primary Malignancies that arise in the parasellar region include germ cell tumors, sarcomas, chordomas,

    and lymphomas. Pituitary carcinomas are rare [23].

    Metastatic disease Metastases to the hypothalamus and pituitary gland account for 1 to 2 percent of sellar

    masses [1,25]. They occur most commonly with breast cancer in women and lung cancer in men, but can be seen

    with many other cancers [26,27]. Symptoms, which occur in approximately 7 percent of patients, include diabetes

    insipidus, anterior pituitary dysfunction, visual field defects, retroorbital pain, and ophthalmoplegia [25]. Survival in

    36 patients in one series averaged six months [27].

    Cysts Rathke's cleft, arachnoid, and dermoid cysts can produce sellar enlargement, possibly resulting in visual

    impairment, diabetes insipidus, anterior pituitary hormonal deficiencies, and hydrocephalus. (See

    "Craniopharyngioma".)

    Abscess Pituitary abscesses, which are rare, can occur in a normal or diseased pituitary gland. In a series of 24

    patients, 16 (33 percent) presented with symptoms and physical findings consistent with a pituitary mass, while

    only eight had features suggestive of infection (fever, leukocytosis, meningismus) [28]. Imaging studies including CT

    and MRI were unable to distinguish between pituitary abscess and pituitary adenoma. As a result, most patients

    were diagnosed at the time of surgical expl

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