L1 Pathology of the Hypothalamus and Pituitary Flashcards
What is hypothalamus? And where it is located ?
The hypothalamus is a region of the brain composed of many small nuclei
The almond-sized hypothalamus is located
- below the thalamus
- above the brainstem.
What are hypothalamus functions ? 7
- Conduit between the nervous and endocrine systems via the pituitary gland (hypophysis),
- Controls the release of 7 major hormones by the hypophysis
- Temperature regulation
- Control of food and water intake
- Sexual behavior and reproduction
- Mediation of emotional responses.
- Produce Antidiuretic Hormone (ADH) and Oxytocin (OXT), and transport them to the posterior pituitary
What are the causes of Hypothalamic insufficiency ?
- irradiation of brain for nasopharyngeal tumors.
- Inflammatory disorders and infections, sarcoidosis, tuberculous meningitis
What are Hypothalamic Suprasellar Tumors?
- Gliomas
- Craniopharyngiomas.
- Rathke cleft cyst
What is Rathke’s cleft cyst ?
It is a benign fluid-filled cyst found on the pituitary gland/Hypothalamus produced due to improper development of RATHKE pouch
What is the histology of Rathke cleft cyst ? And how it will damage the norma glands ?
- Lined by ciliated cuboidal epithelium with occasional goblet cells
- anterior pituitary cells ( as the normal cleft is within the anterior lobe )
So they can accumulate proteinaceous fluid and expand, compromising the normal gland
What are Craniopharyngiomas ?
A type of brain tumor derived from ( pituitary gland embryonic tissue ) appears as
- Encapsulated
- solid, cystic
- sometimes multiloculated
What are the histological features of craniophryngioma ?
- Nests ,cords of stratified squamous epithelium,“Palisading” at the periphery.
- Compact, lamellar keratin formation (“wet keratin”)
- Calcification
What are the cells and hormones of Anterior Lobe (Adenohypophysis) ?
- Somatotrophs- human growth hormone (hGH)
- Gonadotrophs- Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
- Lactotrophs- Prolactin (PRL)
- Corticotrophs- Adrenocorticotropic hormone (ACTH) and melanocyte-stimulating hormone (MSH).
- Thyrotrophs- Thyroid-stimulating hormone (TSH)
What is the function of GH ( somatotropin ) ?
stimulates tissues to secrete hormones that stimulate body growth and regulate metabolism.
What are the functions of LH & FSH ?
- Stimulate secretion of estrogen and progesterone
- Stimulate secretion of testosterone in the testes.
- maturation of egg cells in the ovaries
- stimulate sperm production
What are the causes of Hyperpituitarism and Hypopituitarism ?
Hyperpituitarism : ( most common is tumor either adenoma or carcinoma )
- pituitary adenoma (mostly)
- hyperplasia
- carcinomas of the anterior pituitary
Hypopitutarism :
- Non functional pituitary adenoma
- destructive processes, including :
* ischemic injury
* surgery
* radiation
* inflammatory reactions
What is Pituitary Adenoma? And what is its affects ?
It is a benign tumor Arising in the anterior lobe and it is the most common type of hyperpitutarism
Its enlargement will lead to :
- Compressing optic nerve ( optic chiasma )
- Increase intracranial pressure
- They can destroy sella trucica
What are the main classification of adenoma ?
- Type of hormones
- mostly on hormone
- pluri-hormonal is rare (except PRL + GH which is common ) - Functional vs. non-functional
- Size
- macro >1 cm
- micro < 1 cm
How Large pituitary adenomas, and particularly nonfunctioning ones, may cause hypopituitarism ?
by encroaching on and destroying the adjacent anterior pituitary parenchyma