Pituitary Gland

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Pituitary Gland
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• The normal microscopic appearance of the
  pituitary gland

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The neurohypophysis
The adenohypophysis
The adenohypophysis

• The normal microscopic appearance of the
  pituitary gland

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• The adenohypophysis contains three major cell
  types

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Cell types and function

• Somatotroph GH
• Mammotroph Prl
• Corticotroph ACTH
• Gonadotroph LH , FSH
• Thyrotroph TSH
• Null cells
  non-function

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Hyperpituitarism - Adenoma

• Excess hormone production by the anterior lobe
  majority are Adenomas
• Hyperplasia and carcinoma are rare

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Morphology of Adenoma

• Single and encapsulated
• Microadenoma is lesser than 1 cm
• Macroadenoma is larger than 1 cm , may reach up
  to 10 cm
• May show cystic changes and foci of necrosis
• Expand sella tursica ? pressure effects
  (optic chaisma )
• Pituitary apoplexy haemorrage in the adenoma

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Histology

• Sheets of uniform rounded cells with delicate
  scanty stroma
• Immunohistochimistry Type of secertory hormone

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Types of Pitutary adenoma
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Growth hormone producing adenoma (5)

• Usually large
• Evenly distributed into densely and sparsely
  granulated types
• E/M spherical cytoplasmic granules
• Immuno positive GH - Gh 1/3 and PRL
• Acidophilic cells

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• Growth hormone producing adenoma (5)
• Gigantism (children)
• Acromegaly (adults)
• glucose intolrence , DM,osteoprosis, hypertension

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Prolactin producing adenoma (20-30)

• The most common functioning adenoma
• Majority are microadenamas and sparsely
  granulated
• E/M small secretory granules
• Immuonsv PRL
• Women ---- microadenomas (amenorrhoea,
  glactorrhea syndrom )
• Men and old females ------ macroadenoam(late
  discovery)-----mass effect

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Non secretory (Null cell ) adenoma (20)

• Commenest cause of hypopituitarism
• Large ( macroadenoma) with atrophy of the
  surrounding pituitary tissue
• Immuno Variable 1/3 negative
• Chromphobic cells

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Other rare types of adenomas

• ACTH producing adenoma
• FSH and LH producing adenoma
• TSH-Producing adenoma
• Mixed

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ACTH producing adenoma

• Usually microadenomas
• Give rise to Cushings disease
• E/M ve ACTH
• Basophilic cells
• Nelsonsyndrome(bilatral adrenalectomy----secondry
  ACTH- producing pituitary adenoma

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FSH and LH producing adenoma

• Usually large
• No clinical features due to FSH and LH \
• Mass effect
• High serum FSH and Lh
• E/M secretary granules( 250 nm)
• Immuno ve FSH and LH
• Basophile cells

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TSH-Producing adenoma

• Rare
• Produce TSH

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Carcinoma of the pituitary

• Rare and non functioning
• Differentaited from adenoma by metastasis

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Hypopituitarism

• Causes
• Non_secrertory adenoma
• Pituitary necrosis (sheehans syndrom)
• The empty sella syndrome
• Pituiraty destruction (infection,
  radiation,surgical ablation,metastasis,vasculitis)
  

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• Clinical features
• Deficiency of Gh Dwarfism (children)
• Deficiency of Gonadotrophins stereility
• Deficiency of ACTH or TSH Hypofunction of the
  relevant endocrine glande

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Posterior pituitary syndromes

• Rare
• Due to hypothalamic tumors (gliaoma,gangliocytoma,
  craniopharyngioma,GCT)
• Deficiency of antidiuretic hormone (ADH
  Deficiency)----- diabetes insipidus
  pyolyuriapolydipsia

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