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Craniopharyngioma

contributed by Dr Frank Gaillard on May 2, 2008

System: Central Nervous System
Tag: pituitary

Craniopharyngioma is a type of relatively benign (WHO grade 1) neoplasm which typically arises in the sellar / suprasellar region. 

It derives from remnants of the craniopharyngeal duct (narrowing which separates the Rathke's pouch from the primitive oral cavity), and can occur anywhere along the infundibulum (from floor of the third ventricle, to the pituitary gland).

Demographics and clinical presentation

Craniopharyngiomas demonsrate a bimodal distribution, with the first peak between the ages of 10 - 14 years and the second peak in the 7th decade. There is a similar incidence in both males and females 3. 

Clinical presentation is variable on account of the variable location and size of the tumour. Presenting complaints include:

  • headaches and raised ICP
  • visual symptoms
    • 20% of children 3
    • 80% adults
  • hormonal imbalances
    • short stature and delayed puberty in children
    • decreased libido
    • amenorrhoea
  • behavioural change due to frontal or temporal extension

Pathology

There are two main (quite different) pathological types :

  • adamantinomatous (paediatric)
  • papillary (adult)
Adamantinomatous

Adamantinomatous craniopharyngiomas are seen predominantly in children. They consist of reticular epithelial cells which have appearances reminiscent of the enamel pulp of developing teeth.

There may be single or multiple cysts that are filled with thick oily fluid high in protein, blood products, and/or cholesterol, creating the so called "machinery oil".  "Wet keratin nodules" are a characteristic histological feature. Calcification is usually present (90%).

Papillary 

The papillary sub type, seen in adults, is formed of masses of metaplastic squamous cells. "Wet keratin" is absent. Cysts do form, but these are less of a feature, and the tumour is more solid. Calcification is rare 4.

Location

Typically craniopharyngiomas are located in the suprasellar region. In a minority (10 - 15% 3) the tumour is confined to the sella, which may be expanded. Larger tumours can extend in all directions, frequently distorting the optic chiasm, or compressing the midbrain with resulting obstructive hydrocephalus.

Occasionally, craniopharyngiomas appear as intraventricular, homogeneous, soft-tissue masses without calcification (papillary sub type)

Rare / ectopic locations reported include: floor of 3rd ventricle, nasopharynx, posterior fossa, extension down the cervical spine.

Radiographic features

CT

Typically appears as a heterogeneous mass in the suprasellar region. Calcification (except papillary type) and cysts are very common:

Calcification

  • overall 80 - 87% of craniopharyngiomas are calcified
  • adamantinomatous : 90%
  • papillary : rare 4

Cysts : Seen in 70 - 75% of cases (more frequently in the adamantinomatous type)

MRI

Imaging features can significantly vary depending on the histological sub type 4 and on the size and content of the cysts.

T1 : Signal intensity varies depending on cyst contents, and can appear hyper intense due to protein, blood products, and / or cholesterol (in the classic adamantinomatous type). In the papillary variety, solid components appear iso intense on T1-weighted images.

T1 + GAD : Contrast enhancement is typical, with thin enhancement of the cyst wall, or diffuse heterogeneous enhancement of the solid components.

T2 : Signal is high in both solid and cystic components, but is variable depending on content of fluid. 

T2* : Calcification may be seen as areas of signal drop out and blooming.

MR angiography : May demonstrate displacement of the A1 segment of the anterior cerebral artery. 

Treatment and prognosis

Treatment is usually surgical with radiotherapy especially usefully for incomplete resection. Although benign local recurrence is seen in 7 - 33% of patients 3.

Differential diagnoses