Pituitary gland

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The pituitary gland is known as the master gland.

Divisions:[1]

  • Anterior pituitary (AKA adenohypophysis).
  • Posterior pituitary (AKA neurohypophysis, neural pituitary).

Function

Anterior

Hormones:[2]

  • Growth hormone (GH).
  • Luteinizing hormone (LH)
  • Follicle-stimulating hormone (FSH)
  • Thyroid stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Prolactin (PRL)

Mnemonic: "Go Look For The Adenoma Please" = GH, LH, FSH, TSH, ACTH, PRL.

Posterior

Hormones:[2]

  • Oxytocin.
  • Antidiuretic hormone (ADH).

Anatomy and histology

Anatomy

Basic anatomy (simplified):[3]

  • Anterior:
    • Pars distalis.
    • Pars intermedia.
  • Posterior:
    • Pars nervosa.

Embryological origin:[3]

  • Anterior - Rathke's pouch (roof of mouth).
  • Posterior - diencephalon (ventral aspect).

Images:

Histology

Anterior

  • Acidophils (40% of cells) = red or orange.
    • GH, PRL.
  • Basophils (10% of cells) = basophilic (light blue).
    • TSH, LH, FSH.
  • Chromophobes (50% of cells) = amphophilic (purplish/grey).

Notes:

  • The cellular product (i.e. hormone produced) is not strictly correlated with the cell type.[4]

Posterior

Features:[4]

  • Herring bodies - key feature.
    • Eosinophilic axonal dilations filled with lysosomes and neurosecretory granules.
  • Less cellular.
    • Usually more cellular in perivascular location.

Image: Herring bodies (ouhsc.edu).

DDx for stellar lesions

  • Pituitary adenoma.
  • Rathke cleft cyst.
  • Craniopharyngioma.
  • Germ cell tumour.
  • Meningioma.

Pituitary adenoma

General

  • Classically presents with visual field defects.

Microscopic

Features:[5]

  • Loss of fibrous stroma.

Notes:

  • Smears very well.[6]

Rathke cleft cyst

General

  • Benign counterpart of craniopharyngioma
  • Arises from intermediate lobe of pituitary gland (pars intermedia of pituitary gland).

Radiology:

  • Typically no calcifications.[7]

Radiologic DDx:[7]

Microscopic

Features:

  • Lined by cuboidal or columnar epithelial +occasional goblet cells.[8]
  • +/-Squamous metaplasia.

Image: Rathke's cleft cyst (endotext.org).

Craniopharyngioma

General

  • Develop from remains of Rathke's pouch or squamous epithelial cell rests.[9]

Comes in two flavours:[9]

  • Adamantinomatous type.
  • Squamous papillary type.

Radiology:[9]

  • Calcified (adamantinomatous type).
  • Solid & cystic.

Microscopic

Features (adamantinomatous):[10]

  • Well-circumscribed (or pseudoinvasive border).
  • Multicystic.
  • Small-to-medium sized cells with moderate amount of basophilic cytoplasm.
  • Bland nuclei (with occ. small nucleoli).
  • "Wet" keratin - nests of whorled keratin.
  • Calcifications (non-psammomatous).

Images:

Necrosis

  • Rare.

Causes

  • Sheehan syndrome - secondary to blood loss in childbirth.[11]
  • Syphilis (fetal-maternal transmission).[12]
  • Mollaret's meningitis - very rare.[13] (???)
  • Spontaneous necrosis of pituitary tumours - case reports.[14]

Autoimmune hypophysitis

General

Features:[15]

  • Rare.
  • Autoantigens are unknown.
  • May be misdiagnosed as a nonsecreting adenoma.

Microscopic

Features:[15]

  • Lymphocytic infiltration.

See also

References

  1. ↑ http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/histo.html
  2. ↑ 2.0 2.1 http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Pituitary.html
  3. ↑ 3.0 3.1 URL: http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/histo_pit.html. Accessed on: 31 October 2010.
  4. ↑ 4.0 4.1 Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 26. ISBN 978-0443069826.
  5. ↑ Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 36. ISBN 978-0443069826.
  6. ↑ MUN. 24 November 2010.
  7. ↑ 7.0 7.1 URL: http://emedicine.medscape.com/article/343629-overview. Accessed on: 14 November 2010.
  8. ↑ URL: http://www.endotext.org/neuroendo/neuroendo3/neuroendo3.html. Accessed on: 27 May 2010.
  9. ↑ 9.0 9.1 9.2 Garnett, MR.; Puget, S.; Grill, J.; Sainte-Rose, C. (2007). "Craniopharyngioma.". Orphanet J Rare Dis 2: 18. doi:10.1186/1750-1172-2-18. PMID 17425791.
  10. ↑ Tadrous, Paul.J. Diagnostic Criteria Handbook in Histopathology: A Surgical Pathology Vade Mecum (1st ed.). Wiley. pp. 184. ISBN 978-0470519035.
  11. ↑ URL: http://www.mayoclinic.com/health/sheehans-syndrome/DS00889. Accessed on: 16 November 2010.
  12. ↑ URL: http://pediatrics.aappublications.org/cgi/content/full/104/1/e4. Accessed on: 16 November 2010.
  13. ↑ Dancer CM, Woods ML, Henderson RD, Robertson T, Mungomery M, Allworth A (July 2008). "Mollaret's meningitis and pituitary failure associated with a Rathke's cleft cyst". Intern Med J 38 (7): 609–11. doi:10.1111/j.1445-5994.2008.01709.x. PMID 18715308.
  14. ↑ Sachdev Y, Evered DC, Hall R (April 1976). "Spontaneous pituitary necrosis". Br Med J 1 (6015): 942. PMC 1639254. PMID 1268492. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1639254/pdf/brmedj00512-0028a.pdf.
  15. ↑ 15.0 15.1 Tzou SC, Lupi I, Landek M, et al. (July 2008). "Autoimmune hypophysitis of SJL mice: clinical insights from a new animal model". Endocrinology 149 (7): 3461–9. doi:10.1210/en.2007-1692. PMC 2453094. PMID 18388197. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2453094/.

External links

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