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Craniopharyngioma

 

 

Pathology

Cellular Origin:


Pediatric craniopharyngiomas arise from cellular remnants of the Rathke pouch4,12

Possible histological origins of these tumors may be:

  • Embryonic cell rests of enamel organs located adjacent to the tuber cinereum along the pituitary stalk (most widely accepted theory) – adamantinomatous variant
  • Cellular remnants of Rathke’s cleft – papillary variant
  • Metaplasia in cells of the adenohypophysis (an alternative to derivation from embryonic cell rests)

 

Craniopharyngiomas are classified into three histologic types4,13,17

  • Adamantinomatous
  • Papillary
  • Mixed

 

Intracranial Location and Gross Pathology:

  • Predominantly appears as calcified cystic suprasellar mass which produces visual and pituitary defects
  • May also appear in other locations such as nasal, 3rd ventricular, pineal, and infratentorial
  • Rupture of cyst and leakage of content can cause recurrent asceptic meningitis or Mollaret’s meningitis
  • Often associated with tenacious adherence to adjacent normal vascular and neural structures which makes complete surgical resection challenging.

 

Characteristics:

Adamantinomatous
  • Most common type for all age groups especially the 1st two decades of life

 

  • Cystic filled with dark brown fluids (also known as “crank-case oil”) containing cholesterol crystals.4

 

  • Epithelium resembles long bone tumors containing three distinct layers17:
    1) Basal layer of small basophilic cells
    2) Internal layer of stellate cells in loose connective matrix which is also known as “stellate reticulum”
    3) Top layer of palisading keratinized squamous cells that shed into the cyst cavity forming “wet keratin” which occasionally might be calcified

 

Papillary
  • Common in adults

 

  • Often appears as solid non-calcified mass in 3rd ventricle

 

  • Generally can be separated from adjacent brain structure due to smooth external consistency

 

  • Pathology shows stratified squamous epithelium with papillary projections of epithelial cords17

 

  • Often solid with no cystic component

 

Mixed
  • Combination of adamantinomatous and papillary

 


Summary of histological properties of craniopharyngioma:

Location
  • Extra-axial

Macroscopic appearance
  • Largely cystic
  • Partially solid and cystic

Microscopic appearance
  • Cords of angulated columnar cells resting on a collagen basement membrane

 

  • “Stellate reticulum” and “wet keratin” are prominent features

 

  • Adjacent neuropils can appear quite gliotic with evidence of chronic hemorrhage, presence of Rosenthal fibres and eosinophlic granular bodies (EGBs)

Benign/Malignant
  • Benign

Calcification
  • Yes

Colour
  • Grayish-red

Size
  • Varies

Texture
  • Smooth or finely nodular

Keratin pearls
  • May be present along areas of squamous epithelium

 

  • May become confluent and undergo calcification and/or bone formation

Carcinomatous areas
  • Not yet described

 

Pathology Images:

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