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pituitary adenoma

Classification: 1) microadenomas (< 1 cm) 2) macroadenomas (> 1 cm) Etiology: 1) sporadic 2) familial a) multiple endocrine neoplasia-1 (MEN1) b) familial acromegaly c) McCune-Albright syndrome d) Carney syndrome Epidemiology: - 10% of primary brain tumors - incidentally discovered pituitary neoplasms are common [1] Pathology: (classification) 1) functional neoplasm a) prolactin (PRL)-secreting tumors are the most common b) tumors may also be derived from cells secreting: 1] growth hormone (GH) 2] ACTH 3] TSH 4] gonadotropins (LH, FSH) c) plurihormonal hormones secreting combinations of PRL, GH, TSH, ACTH & glycoprotein hormone alpha subunit d) autonomous hormone secretion (diminished response to feedback inhibition) 2) non-functional neoplasm (1/3) Genetics: 1) nearly all are monoclonal in origin 2) loss of heterozygosity in 20% of sporadic pituitary adenomas a) chromosome 9 b) chromosome 11q13 c) chromosome 13 3) defects in AIP are associated with a) predisposition to pituitary adenoma b) familial isolated pituitary adenoma Clinical manifestations: 1) depends upon size & function (pituitary hormone secretions) 2) galactorrhea, amenorrhea, impotence (prolactinoma) 3) increased hand & foot size, increased spacing of teeth (acromegaly) 4) hyperthyroidism (TSH-secreting adenoma) 5) proximal muscle weakness, facing rounding, centripedal obesity, violaceous striae, diabetes mellitus, hypertension (Cushing's disease, ACTH secretion) 6) headaches, visual field loss*, cranial nerve palsy, diabetes insipidus, hypopituitarism (pituitary mass effect, pituitary apoplexy) * often bitemporal quadrant visual field defect - onset of visual field defect is generally gradual Laboratory: 1) 8 AM serum cortisol* - serum ACTH: elevated with Cushing's syndrome - dexamethasone suppression test for Cushing's syndrome - 1 mg of dexamethasone fails to suppress serum ACTH - 8 mg of dexamethasone suppresses urinary free cortisol 2) serum TSH, serum T4, free T4* 3) serum prolactin* a) elevated with prolactinoma; > 200 ng/mL confirms diagnosis b) if < 200 ng/mL, also consider hypothyroidism 4) serum IGF-1*: elevated with acromegaly 5) growth hormone suppression test - failure of oral glucose to suppress serum GH is consistent with acromegaly 6) ADH (serum sodium, serum osmolality, urine sodium, urine osmolality) 7) serum LH serum FSH, 8 AM serum testosterone (male) serum estradiol (female) 8) AIP gene mutation (familial pituitary adenoma) * initial testing for pituitary incidentaloma [1] Radiology: - MRI of the sella turcica if pituitary mass effect suspected - first test after hydrocortisone administration (see pituitary apoplexy) [1] - if bitemporal hemianopia, MRI neuroimaging with gadolinium contrast when renal function CKD3 or better [7] - repeat MRI at 6 months for incidentally discovered asymptomatic non-functioning pituitary adenoma to rule-out rapidly-growing neoplasm - incidentally found pituitary macroadenomas are associated with 25% risk of enlargement over time, thus serial imaging is indicated [1] Differential diagnosis: - see specific type of pituitary adenoma & pituitary hormone that it secretes - pituitary gland is diffusely enlarged in untreated hypothyroidism & in normal pregnancy [1] Complications: - mass effect of compression on normal pituitary - a large pituitary adenoma can cause panhypopituitarism - pituitary apoplexy - complications of hypophysectomy Management: 1) most functional pituitary adenomas require treatment - exception is microprolactinoma in women with normal menses [1] 2) non-functional tumors require treatment only with well-defined sequellae of tumor growth - asymptomatic pituitary microadenomas do not require treatment [1] 3) neurosurgery is first line treatment for macro-adenomas & hypersecretory adenomas [1] - the exception is prolactinoma for which treatment with a dopamine agonist is preferred [1]l - referral for visual impairment related to adenoma or pituitary apoplexy, mass abuts or compresses the chiasm or optic nerves on MRI 4) radiation therapy a) residual disease after 1st line therapy b) patients who cannot undergo surgery [1] 5) treat hormone deficiencies [1] - stress dose hydrocortisone if undiagnosed complication prior to MRI

Related

acromegaly Carney complex McCune-Albright syndrome multiple endocrine neoplasia type-1 (MEN-1); multiple endocrine adenomatosis; Wermer Syndrome

Specific

pituitary adenoma/ACTH secreting pituitary adenoma/ADH secreting pituitary adenoma/FSH secreting pituitary adenoma/GH secreting (somatotrophinoma) pituitary adenoma/LH secreting pituitary adenoma/non-secreting pituitary adenoma/prolactin secreting (prolactinoma) pituitary adenoma/TSH secreting pituitary incidentaloma

General

adenoma pituitary neoplasm

Database Correlations

OMIM 102200

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2006, 2009, 2012, 2015, 2018, 2022. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  2. Harrison's Online, Chapter 370, McGraw-Hill, 2002
  3. Korbonits M, Storr H, Kumar AV Familial pituitary adenomas - who should be tested for AIP mutations? Clin Endocrinol (Oxf). 2012 Sep;77(3):351-6. PMID: 22612670
  4. Vasilev V, Daly AF, Petrossians P, Zacharieva S, Beckers A Familial pituitary tumor syndromes. Endocr Pract. 2011 Jul-Aug;17 Suppl 3:41-6. Review. PMID: 21613050
  5. Tritos NA, Miller KK Diagnosis and Management of Pituitary Adenomas. A Review. JAMA. 2023;329(16):1386-1398 PMID: 37097352 https://jamanetwork.com/journals/jama/fullarticle/2804060
  6. NEJM Knowledge+ Endocrinology
  7. NEJM Knowledge+ Nephrology/Urology
  8. Molitch ME. Diagnosis and treatment of pituitary adenomas: a review. JAMA. 2017;317:516-524. PMID: 28170483
  9. NINDS Pituitary Tumors Information Page https://www.ninds.nih.gov/Disorders/All-Disorders/Pituitary-Tumors-Information-Page https://jamanetwork.com/journals/jama/fullarticle/2812017