Craniopharyngioma classification

There are two subtypes of craniopharyngioma based on the histological and imaging features: adamantinomatous and papillary.

• Craniopharyngiomas are believed to be derive from Rathke cleft rather than squamous cell rests. ^[1]

• Craniopharyngiomas are classified according to their histologic appearance.
• The histological appearances of the two pathological subtypes are different, accounting for the different imaging features.
• The subtypes are said to differ not only in appearances, but also in prognosis and epidemiology.^[2]

• Adamantinomatous

• • This type is seen predominantly in children.^[1]
  • It consists of reticular epithelial cells which have appearances reminiscent of the enamel pulp of developing teeth.
  • There may be single or multiple cysts filled with thick oily fluid high in protein, blood products, and/or cholesterol, creating the so called “machinery oil”.^[3]
  • “Wet keratin nodules” are a characteristic histological feature.^[4]
  • Calcification is usually present in 90% of the cases.
  • They are more locally aggressive.
  • It has higher rate of recurrence.
  • Activating beta-catenin gene mutations are found in adamantinomatous tumors.^[5]

• Papillary

• • The papillary subtype is seen almost exclusively in adults.^[1]
  • It is formed of masses of metaplastic squamous cells.^[4]

• • “Wet keratin” nodule is absent.^[6]
  • Cysts do form, but these are less of a feature, and the tumor is more solid.^[3]
  • Calcification is uncommon or even rare.^[4]
  • They are less locally aggressive.
  • It has lower rate of recurrence.
  • BRAF V600E mutations are observed in papillary craniopharyngiomas.
• Mixed
  • 15% of them share imaging features and prognosis similar to the adamantinomatous subtye.^[7]

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