Craniopharyngioma
A craniopharyngioma is a type of relatively benign (WHO grade I) 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).
Epidemiology
There is a bimodal distribution, with the first peak between the ages of 10 - 14 years and a second peak in the 5th to 7th decades. There appears to be a similar incidence in both males and females 3.
Clinical presentation
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
- diabetes insipidus
- behavioural change due to frontal or temporal extension
Pathology
There are two main (quite different) pathological types :
- adamantinomatous (paediatric)
- papillary (adult)
Adamantinomatous
This type is seen predominantly in children. 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". "Wet keratin nodules" are a characteristic histological feature. Calcification is usually present : ~ 90%.
Papillary
The papillary sub type is seen in adults and 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 uncommon 4.
Location
They are typically located in the suprasellar region although intrasellar extension can be seen in ~ 1/5th of cases. In a minority (5 - 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 seeb as a heterogeneous mass in the suprasellar region. Calcification (except for the papillary type) and cysts are very common:
Calcification
- overall 80 - 87% of craniopharyngiomas are calcified
- they occur in a stippled pattern
- adamantinomatous : 90%
- papillary : rare 4
Cysts : Seen in 70 - 75% of cases (more frequently in the adamantinomatous type)
MRI
MR 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
- C+ (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
- MR spectroscopy : cyst contents may show a broad lipid spectrum
Treatment and prognosis
Treatment is usually surgical with radiotherapy especially useful for incomplete resection. Although benign local recurrence is seen in 7 - 33% of patients 3.
Differential diagnoses
- Rathke's cleft cyst
- pituitary macroadenoma with cystic change
- intracranial teratoma
See also
Differential for a suprasellar mass
