Hypothalamic and Pituitary Pathology Flashcards Preview

DEMS: Unit III > Hypothalamic and Pituitary Pathology > Flashcards

Flashcards in Hypothalamic and Pituitary Pathology Deck (17):
1

Normal anterior pituitary histology

  • Acinar pattern maintained
  • H&E stain: AP shows different cell types
  • PAS-orange G stain: AP demonstrates greater distinction of cell types (acidophils, basophils, chromophobes)
    • Lateral wings: mostly populated by acidophilic GH secreting cells (maintenance of acinar structure)

2

Normal posterior pituitary histology

  • Manifests eosinophilic fibrillar appearance
    • Occasionally swollen axonal processes (Herring bodies) found
  • Abundant axons by antineurofilament staining
  • Infundibular stalk:
    • Congested, thin-walled, closely juxtaposted hypothalamic hypophyseal portal system

3

Pituitary adenoma pathology

  • Makes hormones without regulation (unchecked in production)
  • Most are sporadic - less than 5% familial
    • Carcinomas exist but are exceedingly rare
    • MEN1, CDKN1B, PRKAR1A, AIP
  • Not caused by end organ signals, not sure what causes them
  • Two sizes
    • Microadenomas
      • < 10 mm
      • Confined to sellar region
      • Can cause some hypofunction or rarely DI
    • Macroadenomas
      • > 10 mm
      • Distort adjacent tissue, erode sella --> symptoms of mass effect (bitemporal hemianopsia)

4

Symptoms of pituitary adenoma

  • Symptoms from hypersecretion
    • Acromegaly
    • Cushing's disease
    • Amenorrhea/galactorrhea
  • Symptoms from mass effect
    • Headaches
    • Vision field defect --> lateral visual field/mesial retinal --> bitemporal hemianopsia
    • Cranial nerve palsies --> ptosis + diplopia
    • Pituitary hormone deficits --> panhypopituitarism
    • Rarely: seizures (lateral growth), stroke, CSF leak

5

Treatment goals of pituitary adenoma

  • Control mass effects
  • Preserve pituitary function
  • Prevent recurrence
  • Relieve symptoms
  • Improve mortality rates
  • Control hormone hypersecretion
  • Use medical therapy, surgery, radiation, careful observation

6

Pituitary adenoma histology

  • Abundant exfoliation of cytologically monotonous cells
  • Nuclear pleiomorphism has no prognostic significance (rarely found)
  • Mitoses rare, but occasionally seen in macroadenomas (slow-growing)
  • Near-signature perivascular arrangement of tumor cells (somewhat simulating ependymoma)
  • Clear-cell appearance somewhat simulates oligodendroglioma
  • Reticulin: single most informative histochemical stain for adenomas
    • Contrasts disrupted reticulin pattern  of adenoma with preserved, nested pattern in normal compressed gland

7

Gonadotroph cell adenoma histology

  • Sheet-like architectural pattern - most common in surgery
    • No acini, sheet-like --> not good prognosis\
  • Higher power magnification: Contains cells with abundant, oncocytic cytoplasm in one area and cells with scant cytoplasm in other regions
  • Immunoreactivity for alpha-subunit
    • Don't know how much is getting out of cell
    • Most patients are not hypersecretory
  • Immunoreactivity for FSH
    • Patchy distribution characteristic
    • Generally no physiologic effect

8

Types and prevalence of of AP tumors

  • Most common at autopsy:
    • Prolactinomas
    • Null cell
    • Gonadotroph
  • Excess hormone production is not OK
  • Different distribution of most common at autopsy vs. those that need surgery 

9

Other types of hypothalamic/pituitary lesions that can lead to pituitary dysfunction (7)

  • Pituitary apoplexy
  • Rathke cleft cysts
  • Lymphocytic hypophysitis
  • Craniopharyngioma
  • Germinoma
  • Meningioma
  • Hamartoma

10

Pituitary apoplexy

  • Old term (apoplexy = collapse)
  • Sudden hemorrhage or infarction of pituitary gland
  • Occurs in 10-15% of pituitary adenomas
  • Occurs in macroadenomas but not always size dependent
  • Can cause AP dysfunction
  • Often occurs in non-clinically evident tumors
  • Symptoms
    • Sudden headache
    • Acute vision changes
    • Ophthalmoplegia
    • Altered mental status

11

Rathke cleft cysts

  • Present two ways
    • Terrible headache with MRI --> have to determine if related
    • Incidental findings
  • Rarely malignant

12

Lymphocytic hypophysitis

  • Autoimmune disorder classically seen in post-partum women
  • Inflammatory condition --> bright on post-contrast studies
  • Completely mimics pituitary adenoma, including on neuroimaging
  • Dx cannot be confidently made until histological confirmation
    • Sheets of cytologically bland pure lymphocytic infiltrates (not neoplastic)
  • Infiltrates hypothalamus + infundibulum which adenoma does not
  • Not a singular disease but rather a collection of different entities

13

Craniopharyngioma

  • Suprasellar calcified mass in pediatric patients
  • Lots in pediatric realm
  • Tends to calcify more than pituitary adenoma

14

Germinoma

  • Germ cell tumors occurs in gonads or midline sites of body 
    • Suprasellar or pineal gland most common
  • WHO grade 4
  • Can be mistaken for adenoma
  • Radiation + chemotherapy
  • Pediatric: causes cognitive problems

15

Meningioma

  • Occur because meninges are nearby
  • Differentiate by where tumor arises from 
    • Determine if gland has distorted shape or normal flat bottom
      • Broad dural base: tumor comes from around the pituitary
      • Broad dural tail
  • Classic location plan, sphenoid alley
  • All kinds of subclassifications/classifications

16

Hamartoma

  • Malformative mass of neurons & glial cells
    • Mass but not true neoplasm
  • Usually incidental finding
  • Overproduction of hypothalamic GnRH or CRH --> precocious puberty 
    • But most cases do not have this clinical feature
  • Surgical resection if symptomatic

17

Clinical findings related to disruption of structures surrounding sella turcica by large pituitary tumor

  • Symptoms from mass effect
    • Headaches
    • Vision field defect --> lateral visual field/mesial retinal --> bitemporal hemianopsia
    • Cranial nerve palsies --> ptosis + diplopia
    • Pituitary hormone deficits --> panhypopituitarism
    • Rarely: seizures (lateral growth), stroke, CSF leak

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