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, ACTH.
  • Chromophobes (50% of cells) = amphophilic (purplish/grey).

Notes:

  • The cellular product (i.e. hormone produced) is not strictly correlated with the cell type.[4]
  • The cells can be typed using IHC; somatotrophs (GH), lactotrophs (PRL), corticotrophs (ACTH), thyrotrophs (TSH), gonadotrophs (FSH, LH).[5]

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 sella turcica lesions

Pituitary necrosis

  • Rare.

Causes of pituitary necrosis

  • Sheehan syndrome - secondary to blood loss in childbirth.[6]
  • Syphilis (fetal-maternal transmission).[7]
  • Mollaret's meningitis - very rare.[8] (???)
  • Spontaneous necrosis of pituitary tumours - case reports.[9]

Images:

Specific entities

Pituitary adenoma

General

  • Clinical:[10]
    • Classically: visual field defects (bitemporal hemianopsia).
    • Others (increased intracranial pressure): headache, nausea, vomiting.

Classification:

  1. Microadenoma <= 1 cm.
  2. Macroadenoma > 1 cm.

Notes:

  • May be classified by what they secrete. Cushing disease is due to pituitary gland hypersecretion of ACTH (due to a pituitary adenoma or CRH hypersecretion from the hypothalamus).[11] Cushing syndrome is hypercortisolism not due to pituitary gland pathology.

Familial pituitary adenomas

A pituitary adenoma may be part of a familial syndrome:[12][13]

Syndrome Gene Notes
Multiple endocrine neoplasia I MEN1 characterized by the 3 Ps: pituitary adenoma, parathyroid adenoma, pancreatic neuroendocrine tumour
MEN-1-like syndrome CDKN1B[14] also known as Multiple endocrine neoplasia IV [14]
Carney syndrome PRKAR1A other findings (mnemonic NAME): nevi, atrial myxoma, myxoid neurofibroma, ephelides (freckles)
Isolated pituitary adenoma[15] AIP classically GH-producing adenoma - leads to acromegaly

Microscopic

Features:[16]

  • Loss of fibrous stroma.
    • The cells of a normal (anterior) pituitary are nested.

Notes:

  • Smears very well.[17]

Images

  • Pituitary adenoma - non-functioning. (WC/KGH)

  • Extensive interstitial and perivascular fibrosis in a pituitary adenoma (WC/jensflorian)

  • Pituitary adenoma - PRL producing, HE. Note the basophilic appearance of the cells (WC/jensflorian)

  • Pituitary adenoma - PRL producing, HE. Extensive regressive changes after after dopamine agonist treatment (WC/jensflorian)

  • Pituitary adenoma - PRL producing, Prolactin IHC (WC/jensflorian)

  • Pituitary adenoma - HGH producing, HE. The cells have a slightly eosinophilic appearance (WC/jensflorian)

  • Sparsely granulated adenoma - HGH producing. Note the numerous fibrous bodies in HE stain (WC/jensflorian)

  • Sparsely granulated adenoma - HGH producing. CK8 IHC highlighting fibrous bodies (WC/jensflorian)

  • Pituitary adenoma - TSH producing. HE stain showing pleomorphism (WC/jensflorian)

  • Pituitary adenoma - TSH producing. TSH IHC can be heterogeneous (WC/jensflorian)

  • Pituitary adenoma - GH producing. (WC/KGH)

  • Pituitary adenoma , HE. This gonadotropin producing adenoma has a papillary architecture (WC/jensflorian)

  • Pituitary adenoma, IHC for FSH (WC/jensflorian)

  • Pituitary adenoma, IHC for LH (WC/jensflorian)

  • Pituitary adenoma , ACTH producing. PAS-O-G stain showing basophilic adenoma cells (WC/jensflorian)

  • Pituitary adenoma , ACTH producing. Strong ACTH IHC in this basophilic adenoma (WC/jensflorian)

  • Pituitary adenoma with vascular pseudorosettes, nonfunctioning (WC/jensflorian)

  • Crooke cell adenoma, HE (WC/Marvin101)

  • Crooke cell adenoma, panCK (WC/Marvin101)

Stains

  • Reticulin - loss of reticulin between tumour cells.

IHC

Variants

  • Corticotroph adenomas exhibiting Crooke's hyaline change: agressive course.[18]

Rathke cleft cyst

General

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

Radiology:

  • Typically no calcifications.[19]

Radiologic DDx:[19]

Microscopic

Features:

  • Lined by a layer of cuboidal or columnar epithelial with cilia.
  • +/-Goblet cells.[20]
  • +/-Squamous metaplasia ~ may be several layers thick.
  • Cholesterol clefts may be seen in association with rupture.[22]

DDx:

Images:

Craniopharyngioma

Main article: Craniopharyngioma

Pituicytioma

Main article: Pituicytoma

Spindle cell oncocytoma

  • Origin: Neurohypophysis or infundibulum.
  • Benign clinical course - WHO grade I.
  • Elongated bipolar, spindle cells.
  • Fascicular or storiform growth patterns.
  • EMA: patchy, S-100+/-ve, GFAP+/-ve, TTF1+ve.
  • It is thought that Spindle cell oncocytomas and Granular cell tumors of the neurohypophysis are variants of Pituicyoma.[23]

Granular cell tumor of the sellar region

Main article: Granular_cell_tumour
  • Origin: Neurohypophysis or infundibulum.
  • Benign clinical course - WHO grade I.
  • Well circumscribed.
  • Polygonal cells with abundant granular cytoplasm.
  • CD68+ve, S-100+/-ve, GFAP+/-ve, TTF1+ve.

  • Granular cell tumor of the sellar region (HE).

Autoimmune hypophysitis

General

Features:[24]

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

Microscopic

Features:[24]

  • 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. ↑ Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1098-9. ISBN 978-1416031215.
  6. ↑ URL: http://www.mayoclinic.com/health/sheehans-syndrome/DS00889. Accessed on: 16 November 2010.
  7. ↑ URL: http://pediatrics.aappublications.org/cgi/content/full/104/1/e4. Accessed on: 16 November 2010.
  8. ↑ 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.
  9. ↑ 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.
  10. ↑ Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1100. ISBN 978-1416031215.
  11. ↑ Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1148. ISBN 978-1416031215.
  12. ↑ Elston, MS.; McDonald, KL.; Clifton-Bligh, RJ.; Robinson, BG. (Aug 2009). "Familial pituitary tumor syndromes.". Nat Rev Endocrinol 5 (8): 453-61. doi:10.1038/nrendo.2009.126. PMID 19564887.
  13. ↑ Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 554. ISBN 978-1416054542.
  14. ↑ 14.0 14.1 Online 'Mendelian Inheritance in Man' (OMIM) 600778
  15. ↑ Korbonits, M.; Storr, H.; Kumar, AV. (May 2012). "Familial pituitary adenomas - Who should be tested for AIP mutations?". Clin Endocrinol (Oxf). doi:10.1111/j.1365-2265.2012.04445.x. PMID 22612670.
  16. ↑ 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.
  17. ↑ MUN. 24 November 2010.
  18. ↑ George, DH.; Scheithauer, BW.; Kovacs, K.; Horvath, E.; Young, WF.; Lloyd, RV.; Meyer, FB. (Oct 2003). "Crooke's cell adenoma of the pituitary: an aggressive variant of corticotroph adenoma.". Am J Surg Pathol 27 (10): 1330-6. PMID 14508394.
  19. ↑ 19.0 19.1 URL: http://emedicine.medscape.com/article/343629-overview. Accessed on: 14 November 2010.
  20. ↑ URL: http://www.endotext.org/neuroendo/neuroendo3/neuroendo3.html. Accessed on: 27 May 2010.
  21. ↑ Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 408. ISBN 978-0443069826.
  22. ↑ URL: http://path.upmc.edu/cases/case177/dx.html. Accessed on: 8 January 2012.
  23. ↑ Mete, O.; Lopes, MB.; Asa, SL. (Nov 2013). "Spindle cell oncocytomas and granular cell tumors of the pituitary are variants of pituicytoma.". Am J Surg Pathol 37 (11): 1694-9. doi:10.1097/PAS.0b013e31829723e7. PMID 23887161.
  24. ↑ 24.0 24.1 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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