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craniopharyngioma

Wednesday 8 September 2004

craniopharyngiomas

Definition: Craniopharyngiomas are benign slow growing tumours that are located within the sellar and para sellar region of the central nervous system. The point prevalence of this tumour is approximately 2/100,000.

Images

- adamantinomatous craniopharyngioma

- papillary craniopharyngioma

Craniopharyngiomas are most frequent in children and adolescents. They are suprasellar, similar to the illustrated epidermoid cyst.

Macroscopy

Grossly, they show a mixture of solid and cystic areas.

Microscopy

Microscopically, they are composed of sheets of squamous epithelial cells and keratin, set in a loose connective tissue stroma.

Islands of keratin often calcify. Water accumulating in the central portion of the epithelial islands causes them to loosen, creating an appearance that resembles adamantinoma.

Cholesterol crystals, formed from break down of keratin, float in the greasy fluid that fills the cysts giving it an iridescent appearance.

Cysts, calcification, and the suprasellar location are the criteria for the radiological diagnosis of craniopharyngiomas.

Clinical synopsis

The onset of symptoms is normally insidious with most patients at diagnosis having neurological (headaches, visual disturbances) and endocrine (growth retardation, delayed puberty) dysfunctions.

The neuroradiological diagnosis is mainly based on the three components of the tumour (cystic, solid and calcified) in the characteristic sellar/para sellar location. Definitive diagnosis is made following histological examination of a surgical specimen.

Physiopathogeny

They and are thought to arise from epithelial remnants of Rathke’s pouch that are trapped in the pituitary stalk. Alternatively, they may represent a form of teratoma. They grow slowly and damage the hypothalamus, compress the optic chiasm, and block the third ventricle, causing endocrine abnormalities, visual disturbances, and hydrocephalus.

Craniopharyngiomas are thought to arise from epithelial remnants of the craniopharyngeal duct or Rathke’s pouch (adamantinomatous type) or from metaplasia of squamous epithelial cell rests that are remnants of the part of the stomadeum that contributed to the buccal mucosa (squamous papillary type).

Clinical differential diagnosis

The differential diagnosis includes other tumours in this region (pituitary adenoma), infectious or inflammatory processes (eosinophilic granuloma), vascular malformations (aneurysm) and congenital anomalies (Rathke’s cleft cyst).

Other common suprasellar tumors are pilocytic astrocytoma and germ cell tumors.

Molecular biology

- BRAF-V600E mutation

Treatment and prognosis

The current treatment is gross total excision of the tumour, if there is no hypothalamic invasion or, in the presence of hypothalamic invasion, a sub-total resection with post-operative radiotherapy.

Endocrine disturbances are normally permanent and need careful replacement. Overall, there is an 80% 5 year survival, though this can be associated with marked morbidity (hypothalamic dysfunction, altered neuropsychological profile).

References

- Garnett MR, Puget S, Grill J, Sainte-Rose C. Craniopharyngioma. Orphanet J Rare Dis. 2007 Apr 10;2:18. PMID: 17425791