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Pituitary Adenoma (Macro vs Micro)

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Overview
  • Pituitary adenomas are the most common form of sellar mass (or tumor), most common age of onset: 35 to 60 years old.
    • Pituitary tumors that are > 10 mm (> 1cm) are macroadenomas.
    • Those less than 10 mm (< 1cm) are microadenomas.
    • Microadenomas constitute the majority of pituitary tumors.
  • The majority of pituitary tumors are non-secretory.
  • The majority of secretory pituitary tumors are prolactin-secreting.
Hormone Pathophysiology
  • Pituitary adenoma from the anterior pituitary is the most common cause of hyperpituitarism.
    • Adenomas may be hyperfunctioning (hormone-overproducting (excess)) or NON-functioning.
Pituitary Adenoma Classification System
Common
Lactotroph (Most common form of pituitary adenoma)
  • Prolactin
    • Galactorrhea
    • Amenorrhea
    • Sexual and fertility dysfunction
Somatotroph
  • GH
    • Acromegaly (gigantism in pediatric population)
    • Nerve entrapment
Corticotroph
  • ACTH
    • Cushing syndrome
Commonly signs: weight gain with a particular prevalence for the midsection/upper back, face "moon face", shoulders "buffalo hump", striae (purple stretch marks), thin, fragile skin, acne.
    • Nelson syndrome
Refers to a syndrome wherein BOTH adrenal glands are removed for treatment of Cushing's disease BUT the pituitary tumor continues to grow and release the hormone ACTH. A key finding is dark skin pigmentation because the skin pigment cells darken in response to the ACTH.
Rare
Thyrotroph
  • TSH
    • Hyperthyroidism
    • CHF
    • Goiter
Gonadotrophy
  • FSH, LH
    • Hypogonadism
    • Hypopituitarism
Symptoms/Complications of Pituitary Masses
Therapy
Pituitary macroadenomas are typically surgically removed via transsphenoidal hypophysectomy, unless they are macroprolactinomas*, which respond to hormonal therapy.
  • Medical therapy is essential for reduction of tumor size, hormonal management (reduction of hormone excess or replacement of hormone deficiency).
References
  • Adesina, Adekunle M., Tarik Tihan, Christine E. Fuller, and Tina Young Poussaint. Atlas of Pediatric Brain Tumors. Springer, 2016.
  • Daroff, Robert B., Joseph Jankovic, John C. Mazziotta, and Scott L. Pomeroy. Bradley’s Neurology in Clinical Practice E-Book. Elsevier Health Sciences, 2015.
  • Gray, Frangoise, Charles Duyckaerts, and Umberto De Girolami. Escourolle and Poirier’s Manual of Basic Neuropathology. OUP USA, 2013.
  • Samuels, Martin A., Allan H. Ropper, and Joshua Klein. Adams and Victor’s Principles of Neurology 10th Edition. McGraw-Hill Education, 2014.
  • Tonn, Jörg-Christian, Manfred Westphal, and J. T. Rutka. Oncology of CNS Tumors. Springer Science & Business Media, 2010.
  • Yachnis, Anthony T., and Marie L. Rivera-Zengotita. Neuropathology E-Book: A Volume in the High Yield Pathology Series. Elsevier Health Sciences, 2012.

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