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Flashcards in Pituitary Deck (15):
1

Anterior Pituitary

SOMATOTROPHS -- GH

LACTOTROPHS -- PROLACTIN

CORTICOTROPHS -- ACTH

GONADOTROPHS -- FSH/LH

THYROTROPHS -- TSH

Makes up 80% of the gland

There is a portal venous system that allows direct transport of releasing hormones from the hypothalamus to the anterior pituitary

Hypo --> GNRH --> Pituitary --> GH
Hypo --> TRH --> Pituitary --> TSH
Hypo --> GnRH --> Pituitary --> FSH/LH

2

Posterior Pituitary

VASOPRESSIN and OXYTOCIN (stored here, both synthesized in hypothalamus)

3

Pituitary Tumor Overview

Make up 10-20% of all intracranial neoplasms

More common in adults, but the MOST FREQUENT TYPE OF INTRACRANIAL TUMOR IN CHILDREN

F > M

Can be "functional" and secrete hormones --> hyperpituitarism (elevated PRL, GH, ACTH)

Visual field defects, headaches, high intracranial pressure

Direct tumor compression may actually DECREASE hormone secretion by the surrounding pituitary tissue, leading to thyroid/adrenal/reproductive issues

All pituitary tumors appear the SAME morphologically and histologically!!! Bland and uniform cells, salt-pepper nuclei, small nucleoli, no mitoses, etc

4

Most common pituitary tumor

PROLACTINOMA

5

Prolactinomas

30% of all pituitary adenomas, most common

Values of prolactin ABOVE 150-200 ng/mL are almost DIAGNOSTIC of prolactinoma

Symptoms!
Women of reproductive age --> AMENORRHEA, GALCTORRHEA (spotaneous milk), INFERTILITY

Postmenopausal Women --> Functionally SILENT

Men - Infertility, diminished libido, impotence

6

Histology of Prolactinomas

Two variations

SPARSELY granulated --> majority (95%), Chrombophobic cytoplasm (doesn't stain well), Perinuclear immunohistochemistry, few small granules and MISPLACED EXOCYTOSIS on EM --> incorrectly exocytose contents between cells, rather than at vascular poles like normal


DENSELY GRANULATED -- 5%; eonsiophilic cytoplasm; diffusely reactive immunohistochemistry, large/dense/pleomorphic granules

7

Treating Prolactinomas

PRL is primarily negatively controlled by DOPAMINE

So we CAN treat with a DA AGONIST!

DA analogs like BROMOCRIPTINE will cause degeneration of the adenoma, shrinking it and limiting PRL secretion

BUT interrupting the treatment will cause RECURRENCE so the treatment MUST BE CONTINUOUS

8

Adenomas associated with GROWTH HORMONE PRODUCTION

3 types -- GH cell adenomas, MIXED GH/PRL adenomas and Pleurihormonal adenomas

Make up 25% of all pituitary adenomas

Symptoms
Younger Patients -- long bone epiphyses have not yet fused, so this can cause GIGANTISM - excess linear growth

Adults -- ACROMEGALY --> growth of bones in the skull, vertebrae, hands, feet; diffuse soft tissue swelling; pronounced bone and jaw protrusion

Complications from acromegaly --> osteoarthritis, carpal tunnel, HTN --> increased risk for diabetes, CHF, hypogonadism

GH cell adenomas are GH+ and PRL-

PLEURIHORMONAL make up the majority of GH secreting adenomas --> HIGHLY ACTIVE!!!! Secrete GH, PRL, and a glycoprotein hormone (TSH, LH, FSH or the common alpha subunit!)

9

ACTH Cell Adenomas

15% of adenomas

Mostly FEMALES (5:1)

High hormonal activity --> CUSHING'S DISEASE (excess Cortisol) is the most common (85% of these tumors) --> can be LETHAL if untreated due to excess cortisol!!!!

10

Symptoms of Cushing's?

Obesity
Mood face
Hirsutism
Acne
HTN
Muscle Weakness
Bruising
Mental Disorders
Osteoporosis

11

Nelson's Syndrome

Without visualizing the usually small ACTH cell tumors, physicians may assume the adrenals are hyperactive and resect them

This can lead to Nelson's Syndrome --> Hyperpigmentation (lots of POMC cleavage products, one of which is melanocyte stim hormone), Sellar Enlargement

WIll only EXACERBATE the problem, because we will remove ANY NEGATIVE FEEDBACK that cortisol provides from the adrenals

Without this, the ACTH production will INCREASE EVEN MORE --> Huge tumor growth!!!! More hormone products!! But without the effects of excess cortisol, since the adrenals were removed

12

Glycoprotein Hormone Cell Adenoma

Leads to the secretion of combinations of TSH, FSH, LH

10% of all pituitary adenomas

TSH producing are RARE (< 1%) and may lead to goiter/other HYPERthyroid problems (TSH is in one cell type, FSH/LH another)

Often affect the elderly, so they are generally functionally silent!

13

Null Cell Adenoma

Pituitary lesions that DO NOT PRODUCE ANY HORMONE

Typically present with symptoms of mass effect

Serum hormone levels are normal or reduced because of tumor displacement of functional tissue

Immunohisto positive for CHROMOGRANIN and SYNAPTOPHYSIN

Eosinophilic cytoplasm and mitochondrial accumulation

14

Pituitary Apoplext

Non-neoplastic pathology

Result of a SUDDEN HEMORRHAGE within a pituitary adenoma leading to INFARCTION OF ENDOCRINE TISSUE

Rapid bleeding leads to a DRAMATIC PRESENTATION with SEVERE HEADACHE, DIPLOPIA, HYPOPITUITARISHM --> neurosurgical emergency!

15

Decreased FSH and LH and menopause?

Decreased FSH/LH is NOT DUE TO MENOPAUSE --> actually, FSH/LH usually INCREASE due to LACK OF ESTROGEN FEEDBACK in menopause!!!