Parapituitary tumours are rare and of these, craniopharyngiomas, evolved embryologically from Rathke's pouch, are the most common (Fig. 2.7). They occur above or, more rarely, in the sella turcica and may be solid or cystic. The majority show calcification above the sella turcica. These tumours may contain an oily fluid containing human chorionic gonadotrophin and cholesterol crystals, and are characteristically lined by squamous epithelial cells. Fifty per cent of cases occur in patients under the age of fifteen years, and patients commonly present with GH deficiency and diabetes insipidus, with or without visual field defects.
