Flashcards in L1 Pathology of the Hypothalamus and Pituitary Deck (31):
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
1. Conduit between the nervous and endocrine systems via the pituitary gland (hypophysis),
2. Controls the release of 7 major hormones by the hypophysis
3. Temperature regulation
4. Control of food and water intake
5.Sexual behavior and reproduction
6.Mediation of emotional responses.
7. 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?
• 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
2. solid, cystic
3. 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”)
What are the cells and hormones of Anterior Lobe (Adenohypophysis) ?
1. Somatotrophs- human growth hormone (hGH)
2. Gonadotrophs- Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
3. Lactotrophs- Prolactin (PRL)
4. Corticotrophs- Adrenocorticotropic hormone (ACTH) and melanocyte-stimulating hormone (MSH).
5. 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 ?
1. Stimulate secretion of estrogen and progesterone
2. Stimulate secretion of testosterone in the testes.
3. maturation of egg cells in the ovaries
4. stimulate sperm production
What are the causes of Hyperpituitarism and Hypopituitarism ?
Hyperpituitarism : ( most common is tumor either adenoma or carcinoma )
1. pituitary adenoma (mostly)
3. carcinomas of the anterior pituitary
1. Non functional pituitary adenoma
2. destructive processes, including :
* ischemic injury
* 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 :
1. Compressing optic nerve ( optic chiasma )
2. Increase intracranial pressure
3. They can destroy sella trucica
What are the main classification of adenoma ?
1. Type of hormones
- mostly on hormone
- pluri-hormonal is rare (except PRL + GH which is common )
2. Functional vs. non-functional
- 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
What are the most common types of adenoma ?
1. PRL adenoma ( 30% most common / lactohrea )
2. Non functional adenoma ( 25% )
What is the prevalence of adenoma in the general population?
the prevalence of pituitary adenomas in the population is estimated to be about 14%, but the vast majority of these lesions are clinically silent microadenomas (pituitary incidentaloma).
What are the gross appearance of adenoma ?
2. Well circumscribed
3. Confined to sella turcica but with expansion it can erode :
* sella turcica
* anterior clinoid processes
What is the histological features of the adenoma ?
• Uniform, polygonal cells arrayed in sheets or cords.
• Supporting connective tissue, or reticulin, is sparse, accounting for the soft, gelatinous consistency of many of these tumors.
• Mitotic activity is usually sparse.
What are the type of The cytoplasm of the tumor cells ?
It can be acidophilic, basophilic, or chromophobic, depending on the type and amount of secretory product within the cells, but it is generally uniform throughout the tumor.
What are atypical adenomas ?
A subset of pituitary adenomas demonstrates:
- elevated mitotic activity (>3%)
- nuclear p53 expression
These features correlate with the presence of TP53 mutations. These tumors have a higher propensity for aggressive behavior, including invasion and recurrence,
What is nuclear stain for mitosis ?
What are the features of "atypical" variant depending on WHO ?
1. MIB-1 proliferative index greater than 3%
2. excessive p53 immunoreactivity
3. increased mitotic activity.
What is special in Pituitary Carcinoma ?
It is rare that can be adenoma or atypical adenoma
The presence of craniospinal or systemic metastases important for diagnosis
What is the origin of Hypopituitarism that is accompanied by evidence of posterior pituitary dysfunction in the form of diabetes insipidus ?
It is almost always of hypothalamic origin.
What are the causes of hypopiturirism ?
• Tumors and other mass lesions
• Traumatic brain injury and subarachnoid hemorrhage
• Pituitary surgery or radiation
• Pituitary apoplexy
• Ischemic necrosis of the pituitary and Sheehan syndrome
What is Pituitary apoplexy ?
Huge non functional adenoma that grows very quickly.
What is Lymphocytic hypophysitis ?
It is a Rare disease that is more common in females due to :
• Inflammatory/autoimmune disorder
And it involves the pituitary gland /pituitary stalk
What are the histological features of lymphocitic hypophysitis ?
1. Lymphocytes (so CD4 and CD8 are used as markers )
2. Plasma cells
3. Epitheloid histocytes
What are the most common Posterior Pituitary Syndromes ?
• Diabetes insipidus.
• ADH deficiency