This is a normal anterior pituitary gland histology. Note the bluish colour of the basophils, and pinkish colour of the acidophils.

This is a histology slide of the posterior pituitary.

The brown-stained cells are cells that secrete Growth Hormones – Somatotropes. The cells are stained for immunochemistry evaluation.

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Pituitary Tumours

**Definition: Neoplasm located in the sella turcica.

Comprises of 10-15% of all intracranial tumours. 27% pituitary glands contain incidental adenomas (very common in people). 1/5 show pituitary abnormality on MRI. Uncommon in children, 2%.

Types of pituitary tumours:

1) Pituitary adenomas from adenohypophyseal – anterior pituitary (most)

2) Pituitary carcinoma (small percentage)

3) Mesenchymal, Neural, Epithelial, Metastases

Pituitary Adenoma

Most common:

1) Prolactinoma – in adults & children

2) ACTH-oma – more frequent in children

Signs & Symptoms – 2 concepts

1) Excessive hormone

  • If it’s a funtioning tumour: high hormone level
  • Non-functioning tumour: normal hormone level

2) Mass effect

  • Intracranial mass: headache
  • Loss of normal anterior pituitary hormone production due to compression
  • Visual field defect: compression of optic chiasma (tunnel vision)
  • Mild hyperprolactinemia (**stalk effect)

Classification

1) Functional – hormone level
2) Histology
3) Ultrastructural
4) Biochemical
5) Imaging
6) Surgical findings

Classification by size (imaging)

Microadenoma – <1cm
Macroadenoma – >1cm
Giant adenoma – >4cm (RARE)

Evaluate growth pattern, expansile, invasive.

Histology

  • Monomorphic (just larger/more. No dysplasia)
  • Uniform round cells
  • Delicate stippled chromatin
  • Inconspicuous nucleoli
  • Moderate amounts of cytoplasm
  • Mitoses: rare
  • Ki67 labelling <3% (determine growth)
  • Atypical variant

Treatment

1) Surgical – Via transphenoidal approach (minimally invasive)

Only perform surgery when:

  • Progressive mass effect (visual loss)
  • Hyperfunction (Cushings, acromegaly, hyperthyroid)
  • Failure of medical treatment
  • Massive acute haemorrhagic necrosis of an adenoma (pituitary apoplexy/Sheehan’s syndrome)

Sheehan’s syndrome – Haemorrhagic & infarcted

2) Medical treatment

Prolactinoma: Give dopamine agonist (inhibits prolactin). Reduces hyperprolactinemia, reduce tumour size.

GH-oma: Somatostatin analogues react with receptors, prevent growth hormone secretion. Does not reduce tumour size.

3) Radiation (Gamma Knife)

Use in:

  • Incomplete surgical resection
  • Recurrent tumors
  • Medically unfit for surgery
  • Secretory tumours uncontrolled by other treatment

Complication:

  • hypopituitarism
  • glioma (tumour of glial cells)
  • sarcoma (malignant cancer of CT)

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Prolactinomas

*Most frequent type

  • Cytoplasm weakly acidophilic
  • Sparsely granulated/densely granulated
  • Dystrophic calcification – pituitary stone

Characterised by: efficiency ( small tumours will also secrete hormone) and proportionality (hormone production proportional to tumour size)

Clinical features:

1) Amenorrhea
2) Galactorrhoea
3) Loss of libido
4) Infertility

These clinical features can also be caused by : prolactinemia, pregnancy, suckling and stress.

Prolactinaemia:

Due to hyperplasia of the lactotroph (secrete prolactin). It can be caused by:

1) Interference with dopamine inhibition (no inhibition of lactotroph)
2) Damage to dopanergic neurons of hypothalamus from trauma (no dopamine)
3) Mass in suprasellar compartment : Stalk effect

Growth Hormone Adenoma

**2nd most common

It will grow to be quite large before it will be clincally symptomatic. It is acidophilic (sparsely/densely granulated)

Immunohistochemistry: GH+ , CK+

Diagnosis:

  • High level of growth hormone
  • High level of IGF-1
  • No suppression of GH with glucose loading

Corticotroph Adenoma

May be basophilic/ acidophilic.

  • Usually small
  • Most often densely granulated & basophilic
  • PAS positive (bcos of carbohydrate content)

Immunohistochemistry: ACTH positive

Clinical features:

  • Cushing’s syndrome (collection of signs & symptoms)
  • Cushing’s disease (if pituitary tumour)
  • Nelson syndrome
    -Largely destructive adenoma develop after surgical removal of adrenal glands
    -Hyperpigmentation (MSH)
    -Mass effect
    -No hypercortisolism

Nelson syndrome
Gonadotroph adenoma

-LH, FSH

Inefficient & variable secretion
No recognisable syndrome

Thyrotroph adenoma

Non-functioning adenomas
-silent

Pituitary Carcinoma

Must show METASTASES.

Suprasellar tumours

Effect: Induced hypo/hyperfunctioning of anterior pituitary / diabetes mellitus / both.

2 main types:

  1. Gliomas from chiasma
  2. Craniopharyngiomas (most)

Craniopharyngioma

It is an epithelial tumours (stratified squamous cell epithelia). It represents a bimodal distribution (5-15 years old & 50 years above). Histologically: 3-4cm, encapsulated, cystic/ solid.

2 variants:

  1. Adamantinomatous

    Stratified squamous epithelium
    Loose reticulum
    Compact lamellar keratin (wet keratin)
    Ca
    lcification
    Chronic inflammation
    Cholesterol rich yellowish fluid – machinery oil fluid
  2. Papillary

    Solid & papillary sheets of squamous epithelium
    No keratin
    No calcification
    No cysts
    No reticulum

Malignant transformation of craniopharyngiomas are RARE, unless there has been radiation.


terri

Terri is obsessed with making medical school as painless as possible. She studies and compiles medical school notes in a concise, easy-to-understand format. She also enjoys reading contributions by others. She is an investor in sustainability projects. Her ideal weekend is wine tasting and experimenting on bread-making. She has yet to master the art of Sourdough baking.

2 Comments

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Casey Surgical Arts · December 3, 2016 at 9:19 am

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