CRANIOPHARYNGIOMA

BY DR.ROOHIA

craniopharyngioma

Inroduction Frequency Pathology Clinical presentation

introduction

“Craniopharyngioma” was the name introduced by Cushing for tumors derived “from epithelial rests ascribable to an imperfect closure of the hypophysial or craniopharyngeal duct.”

Craniopharyngiomas are benign tumors that occur at the base of the brain, above the pituitary gland.

Craniopharyngioma is a slow-growing, extra-axial, epithelial-squamous, calcified, cystic tumor. ( WHO grade I)

arising from remnants of the craniopharyngeal duct and/or Rathke cleft and occupying the (supra)sellar region.

Frequency

INCIDENCE: Annual incidence rate being between 0.5 and 2.5

new cases per million population per year. Age: Bimodal- 5-10yr & 50-60yr Adults- 1-3% of intracranial tumors - 13-15% sellar or supra sellar Childrens-56% of sellar or supra sellar tumors. Sex: slight male predominance 55% Race: Higher in Africa,Far east & Japan(18,16,10.5%)

ETIOLOGY

The embryogenetic theory The embryogenetic theory relates to the

development of the adenohypophysis and transformation of the remnant ectoblastic cells

of the craniopharyngeal duct and the involuted Rathke pouch. Rathke pouch and the infundibulum develop

during the fourth week of gestation and together form the hypophysis.

Rathke cleft, together with remnants of the craniopharyngeal duct, can be the site of origin of craniopharyngiomas.

The metaplastic theory The metaplastic theory relates to the

residual squamous epithelium which may undergo metaplasia.

The dual theory explains the craniopharyngioma spectrum

1. adamantinous type (most prevalent in childhood) to embryonic remnants.

2. adult type (squamous papillary) to metaplastic foci derived from mature cells of the anteriorhypophysis.

3. Mixed type – 15%

MOLECULAR BIOLOGY

Some craniopharyngiomas are monoclonal in origin, and cytogenetic abnormalities have been reported in chromosomes 2 and 12.

Mutations of the β-catenin gene have been identified in 70% of adamantinomatous craniopharyngiomas.

HISTOLOGY

GROSS: smooth lobulated capsule Solid- calcified Cystic-machine oil (crankcase oil)

ADAMANTINOMATOUS

Epithelial lesion with peripheral palisading of basal squamous epithelium surrounding loosely arranged epithelial cells, the so-called "stellate reticulum" and nodules of keratin and variable calcification are typical histologic features of a craniopharyngioma.

These nodules are referred to as "wet" keratin because of the plump appearance of the keratinocytes.

PAPILLOMATOUS TYPE

composed of simple squamous epithelium and fibrovascular islands of connective tissue.

Mixed type

The brain parenchyma that surrounds both variants of craniopharyngioma is typically gliotic and often shows profuse numbers of eosinophilic Rosenthal fibers.

Rosenthal fibers in neuropil surrounding the craniopharyngioma.

Differences between adamantinomatous and papillary

craniopharyngiomasAdamantinomatous craniopharyngiomas More common Occur at a younger age

Commonly calcified Commonly cystic and filled

with cholesterol-rich fluid or soft necrotic debris.

A palisading layer of basaloid epithelium surrounds irregularly arranged cells that resemble the stellate reticulum of the epidermis. These nests may be solid but often form a complex trabecular network of microcysts. Bands of fibrous tissue weave between nests of epithelial cells and around cyst

Keratin nodules are commonly seen.

Papillary craniopharyngiomas Less common Occur at an older age Calcification is less

common Commonly solid. Squamous epithelial

nests that surround loose fibrovascular tissue rather than microcysts create a solid tumor with a pseudopapillary pattern.

Keratin nodules are not seen.

VASCULAR SUPPLY

 A1 segment of the anterior cerebral artery.

proximal portion of the posterior communicating artery.

intracavernous meningohypophyseal arteries.

CLINICAL PRESENTATION Anterior extension to

the prechiasmatic cistern and subfrontal spaces; posterior extension into the prepontine and interpeduncular cisterns, cerebellopontine angle, third ventricle, posterior fossa,and foramen magnum; and laterally toward the subtemporal spaces.

headaches and raised ICP visual symptoms

20% of children 80% adults

hormonal imbalances short stature and delayed

puberty in children decreased libido amenorrhoea diabetes insipidus

behavioural change due to frontal or temporal extension

prechiasmal localization typically results in associated findings of optic atrophy (eg, progressive decline of visual acuity and constriction of visual fields).

retrochiasmal location commonly is associated with hydrocephalus, with signs of increased intracranial pressure (eg, papilledema and horizontal double vision).

intrasellar craniopharyngioma usually manifests with headache and endocrinopathy.

Tumour classification

Hoffman et al: sella turcica optic chiasm floor of 3rd ventricle 1. Prechiasmatic 2. Retrochiasmatic 3. Subchiasmatic 4. intraventricular

Sammi et al: vertical projection Grade I- intra sellar/infra diaphragmatic Grade II-Occupying cistern with/with out

an intrasellar component. Grade III- Lower ½ of 3rd ventricle Grade IV- Upper ½ of 3rd ventricle Grade V- Reaching the septum pllucidum

or lateral ventricle.

Differential diagnosis

Rathke's cleft cyst no solid / enhancing component unilocular majority are completely or mostly intrasellar 

Pituitary macroadenoma (with cystic degeneration / necrosis) can look very similar usually has intrasellar epicentre with pituitary fossa

enlargement rather than suprasellar epicentre despite occasional presence of T1 bright cystic regions,

calcification in these cases is often absent (whereas most adamantinomatous craniopharyngiomas are calcified)

Intracranial teratoma presence of fat is helpful, but requires fat saturated

sequences or CT of confirm

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