SM_173b: Hypothalamus-Pituitary Histology / Pathology Flashcards
____ plays a central role in modulating the endocrine system along with the hypothalamus
Pituitary plays a central role in modulating the endocrine system along with the hypothalamus
- Pituitary connected to hypothalamus via pituitary stalk, confined by sella turcica and sellar diaphragm
- Activity intimately related to the hypothalamus via hypothalamic-hypophyseal portal venous system (anterior pituitary) and direct axonal projections (posterior pituitary)
_____, _____, _____, and _____ of the hypothalamus control the anterior pituitary
Arcuate nucleus, paraventricular nucleus, ventromedial nucleus, and dorsal nucleus of the hypothalamus control the anterior pituitary
- Arcuate nucleus: GHRH, dopamine, GnRH
- Paraventricular nucleus: TRH, CRH, GnRH, somatostatin
- Ventromedial nucleus: TRH, GnRH
- Dorsal nucleus: TRH, GnRH
____ and ____ of the hypothalamus control the posterior pituitary
Supraoptic and paraventricular nuclei of the hypothalamus control the posterior pituitary
- Oxytocin and vasopressin
Pituitary consists of the ____, ____, and ____
Pituitary consists of the anterior pituitary (adenohypophysis), posterior pituitary (neurohypophysis), and pars intermedia
Anterior pituitary is populated by ____ and cells are compartmentalized into ____
Anterior pituitary is populated by epithelial cells containing trophic hormones and cells are compartmentalized into small acini by a reticulin network
- Many different cell types
Posterior pituitary is populated by ____ and ____ and axons are supported by ____
Posterior pituitary is populated by axons and axon terminals and axons are supported by specialized glial cells termed “pituicytes”
- Originate in neurons in the supraoptic and paraventricular nuclei of hypothalamus
- Axonal expansions visible as finely granular rounded to ellipsoidal structures (Herring bodies)
____ and ____ are histological features present the posterior pituitary
Herring bodies and pituicytes are histological features present the posterior pituitary
_____ is the likely site of Rathke’s cleft cysts
Pars intermedia is the likely site of Rathke’s cleft cysts
- Cystic change common
- Vestigial
- At interface of adenohypophysis and neurohypophysis
Anterior lobe of pituitary blood supply is primarily ____
Anterior lobe of pituitary blood supply is primarily the low pressure portal venous circulation from hypothalamus
- Facilitates delivery of hypothalamic releasing hormones to anterior pituitary target cells
- Low pressure renders the anterior lobe vulnerable to ischemic insults (hypotension, elevated ICP)
Posterior lobe of pituitary receives blood mainly from ____
Posterior lobe of pituitary receives blood mainly from direct branches of inferior hypophyseal arteries
Pituitary has ____ origins
Pituitary has dual ectodermal origins
- Anterior pituitary: from oral ectoderm (Rathke’s pouch, an extension of the developing oral cavity)
- Neurohypophysis: from neural ectoderm (ventral outgrowth of the hypothalamic floor)
____ are the most common cause of hyperpituitarism
Pituitary adenomas are the most common cause of hyperpituitarism
- Most common tumors of anterior pituitary
- Pathogenesis uncertain in most cases: few cases associated with MEN-1
- Manifestations related to secretion of excess hormone, hypopituitarism, mass effect
- Pathological classification based on immunohistochemical profile and other selected morphological features
Describe general morphological features of pituitary adenomas
General morphological features of pituitary adenomas
- Cytoplasm of constituent cells is monomorphous compared to non-neoplastic gland
- Paucity of reticulin network
- Low mitotic activity
- Atypical adenomas: ki-67 labeling index > 3%
Describe the types of pituitary adenoma
Types of pituitary adenoma
- Prolactin
- Growth hormone
- ACTH
- Gonadotropin
- Thyrotroph
- Nonfunctioning
Prolactin-producing adenomas cause ____ in women and ____ in men
Prolactin-producing adenomas cause amenorrhea / galactorrhea in women and impotence / loss of libido in men
- Microadenomas or macroadenomas
- Most common variant
- Usually diagnosed earliest in women of reproductive age
Describe prolactinoma histology
Prolactinoma histology
- Sparsely granulated
- Dystrophic calcification (pituitary stone)
- Elevated prolactin levels due to tumor secretion must be distinguished from stalk effect: levels < 150 ng/MI may represent stalk effect
- Most response to bromocriptine and related drugs (cabergoline)
Describe growth hormona (somatotroph cell) adenomas
Growth hormona (somatotroph cell) adenomas
- Most are macroadenoma
- Sparsely granulated (fibrous bodies) or densely granulated
- Prolactin reactivity often present
- Elevated IGF-1 leads to gigantism and acromegaly
This is a ____ adenoma
This is a densely granulated growth hormone adenoma
This is a ____ adenoma
This is a sparsely granulated growth hormone adenoma
This is a ____ adenoma with ____
This is a sparsely granulated growth hormone adenoma with fibrous bodies
Describe ACTH-producing adenomas
ACTH-producing adenomas
- Usually microadenomas
- Basophilic, densely granulated, strongly PAS and ACTH-reactive
- Associated with hypercortisolism
- Cushing syndrome: hypercorticism regardless of cause
- Cushing disease: hypercorticism due to ACTH adenoma
- Nelson syndrome: enlargement of ACTH adenoma after removal of both adrenal glands
This is an ____ adenoma
This is an ACTH corticotroph cell adenoma
Describe gonadotroph (FSH-LH) cell adenoma
Gonadotroph (FSH-LH) cell adenoma
- Macroadenomas
- Many occur in the setting of hypogonadism
- Symptoms usually referable to mass effect
- Elevated alpha-subunit common
____ are usually macroadenomas and a rare cause of hyperthyroidism
Thyrotroph (TSH) cell adenomas are usually macroadenomas and a rare cause of hyperthyroidism
