Craniopharyngioma

Abstract

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

Figure 1

CT of a craniopharyngioma. This unenhanced CT shows a calcified cystic structure in the supra sellar region, together with hydrocephalus

Figure 2

Enhanced T1 weighted MRI's of craniopharyngiomas. a. Apredominantly solid sellar/supra sellar tumour that is discrete fromthe hypothalamus (grade 0). b. A predominantly cystic sellar/suprasellar tumour that is distorting but not invading the hypothalamus (grade 1). c. A predominantly solid sellar/supra sellar tumour. The hypothalamus is not visible because of tumour invasion (grade 2).