Patho L1 Pituitary Adenomas Flashcards
What gene encodes Gs-alpha subunit?
GNAS
What are the effects of GNAS mutation?
Evasion of GTPase activity of Gs-alpha leading to continuous activity of Gs-alpha
What type of cells most commonly constitute pituitary adenomas?
Somatotrophs sometimes corticotrophs
Explain the microscopic features of Pituitary adenomas?
1) LM: cellular monomorphism
2) reticular stain: reduces reticular tissue
3) EM: Granules filled with hormones
4) Immunohistochemistry: detects what type of hormones in granules
What is pituitary apoplexy?
It is an acute hemorrhage into an adenoma with rapid enlargement and loss of consciousness
What is the most common hyperfunctioning Pit.adenoma ?
Prolactinoma
Explain the histology of prolactinoma
LM: chromophobic or weak acidophilic (due to mammotrophs)
EM: sparse granulation
Immunohistochemistry: prolactin (+)
Manifestations of Prolactinomas pre and post menopause?
Pre : microadenomas, hyperfunctioning ( amenorrhea, galactorrhea, less libido)
Post: macroadenomas causing local mass effect (visual, intracranial pressure, hypopituitarism)
Tell me about GH adenomas and the histology.
Second most common, can present both GH and PRL
LM: chromophobic/acidophilic
Histochemistry: GH (+)
EM: densely granulated
What are the manifestations of GM adenoma?
Gigantism (before epiphyses close) or acromegaly (after)
What is prognathism and to what condition is it related ?
It is protrusion of the jaw (due to enlargement) and occurs in acromegaly
Histology of corticotroph cell adenoma
Mostly microadenomas
LM: basophilic
Histochemistry: ACTH (+)
What are the manifestations of corticotroph cell adenoam
Either silent or hypercotisolism causing Cushing’s syndrome
What is nelson syndrome?
It is characterized by increased ACTH due to loss of feedback inhibition after bilateral adrenalectomy
No cushing’s since no cortisol
How does FSH producing adenomas cause damage?
Local Mass effect
