Pathology: Pituitary, hypothalamus and pineal gland Flashcards
The anterior lobe of the pituitary is also known as the…
adenohypophysis
The posterior lobe of the pituitary is also known as …
neurohypophysis
What are the three major morphologic cell types found in the anterior pituitary based on staining ?
Acidophils (eosinophilic)
Basophilic
Chromophobe
What hormone producing cells of the anterior pituitary are considered Acidophilic (eosinophilic) ?
Somatotrophs: produce Growth Hormone
Latotrophs: Produce PRL
What hormone producing cells of the anterior pituitary are considered Basophils ?
Corticotrophs: Make ACTH, POMC, MSH and Endorphins
Gonadotrophs : Make FSH and LH
What hormone producing cells of the anterior pituitary comprise half of the hormone cells found in the pituitary ?
Somatotrophs (GH)
What hormone producing cells of the anterior pituitary are considered Chromophobes ?
Thyrotrophs : Make TSH
Technically, these cells are pale blue but are less chromatic then the basophils
What is the hallmark of ‘healthy’ pituitary tissue on microscopy ?
BONUS: what kind of tissue is the Ant. pit comprised of ?
The presence of all three cell types (if there is a portion dominated by a single cell type, then it usually points to some kind of adenoma)
BONUS: Ectoderm
The posterior pituitary is called the neurohypophysis because….
It is derived from neural tissue, it is a direct extension of the hypothalamus
What are the modified glial cells of the posterior pituitary known as ? HITSO BONUS: what would they stain with ?
pituicytes
Bonus: GFAP
What are the two peptides that are secreted by the posterior pituitary (produced in the hypothalamus, just released in post. pit.) ?
Oxytocin Arginine Vasopressin (ADH)
Hyperpituitarism (excessive secretion of trophic hormones) is caused by which 5 pathologies ?
Pituitary Adenoma (Only real lesion seen in pit.) Hyperplasia of Pit. Carcinomas of Ant. Pit Ectopic Production of Pit. hormones Hypothalamic disorders.
Hypopituitarism (decreased secretion of trophic hormones ) is typically caused by …
Destructive proscess: Iscehmia Surgery/Radiation Inflammation Non-Functional adenomas
What are the three basic symptoms seen in patients with an enlarged pituitary (adenoma, hyperplasia etc.) ?
ALL ASSOCIATED WITH MASS EFFECT:
Head Ache
Temporal Field Vision Defects
Pituitary dysfunction: Hyperpituitarism (functional ), Hypopituitarism (non-functional)
Sellar expansion with bony erosion and disruption of the diaphragmatic sell of sella turcica are all signs of what condition ?
Enlarged
Why does enlargement of the pituitary cause bilateral temporal hemianopsia ?
Compresses the desiccating fibers of the optic chiasm (optic chasm is anterior to pituitary) by extending superiorly through the diaphragm sella.
Where do most adenomas arise in the pituitary ?
Anterior lobe
What is the most common cause of hyperpituitarism ?
Pituitary adenoma (anterior lobe)
Functional pituitary adenoma
Functional: Makes hormones (in excess) , shows clinical manifestations
Non-Functional pituitary adenoma
IHC/ultrastructural demonstration of hormone production
Leads to Hypopituitarism
Clinically, more associated with Mass Effect
Show Abrupt enlargement of the tumor secondary to acute hemorrhage (pituitary apoplexy)
What is the most common form of pituitary adenoma leading to Hyperpituitarism?
Prolactin Secreting Adenoma
Second most common is GH Secreting, these two are often seen at the same time. Why ? Both Acidophils ?
What age of person is more likely to get Pituitary Adenoma with hyperpituitarism ?
Adults age 35-60
microadenoma
less than 1cm
Macroadenoma size ?
greater than 1 cm
Which is more invasive, micro or macro adenoma ?
Microadenoma
Micro or Macroadenoma :Silent and hormone-negative, come to clinical attn at a later stage.
Macroadenoma
Are pit. adenomas well circumscribed lesions ?
YES
Are pit. adenomas encapsulated ?
NO
What region of the anatomy is the pituitary confined to ? (may extend beyond this when transformed in adenoma can infiltrate surrounding tissues)
The sella turcica
In large adenomas, why do you see regions of necrosis and hemorrhage in the lesion ?
The tumor is outgrowing its blood supply so portion of it will die or burst.
What surrounding tissues can pit. adenomas infiltrate ?
Cavernous and sphenoid sinuses
Dura, and on occasion, the brain
What kind of supporting connective tissue do you often see in pit. adenoma ?
Sparse Reticulin (Soft, gelatinous consistency )
What cellular morphology pattern do you often see in pit. adenoma ?
Monomorphism (only one type of the three staining cell types are typically present)
What normal connective tissue constituent is often missing or in low concentration with pit.adenoma ?
Reticulin network
How are cells arranged in pit. adenoma ?
Relatively uniform, polygonal cells arrayed in sheets or cords
Eosinophilic monomorphism: what cells are most likely involved in this adenoma ?
LACTOTROPHS (Prolactinomais most common)
Could also be GH Secreting Adenoma
Basophilic monomorphism: what cells are most likely involved in this adenoma ?
Corticotrophs or Gonadotrophs (possibly thyrotrophs but this is VERY RARE, also these are more chrmophobic)
What are the two major morphologies of Prolactinoma ?
Sparsely granulated prolactinoma: more chromophobic, weakly acidophilic
Densely granulated prolactinoma: Strongly acidophilic