Craniopharyngioma

Craniopharyngioma is a histologically benign, WHO grade 1 epithelial tumour arising from remnants of the craniopharyngeal duct, which develops from Rathke pouch tissue. “Benign” describes its histology, not its clinical behaviour. A tumour only a few centimetres across can compress the optic chiasm, pituitary, hypothalamus, or third ventricle and produce permanent neurological and endocrine disability. There are two biologically distinct subtypes. Adamantinomatous craniopharyngioma is more common in children and is often cystic, calcified, and associated with CTNNB1 or beta-catenin pathway alterations. Its cyst fluid may have a thick, proteinaceous, “machine-oil” appearance. Papillary craniopharyngioma occurs almost exclusively in adults, is usually more solid and less often calcified, and is driven characteristically by a BRAF V600E mutation. The age pattern is therefore bimodal, with a childhood peak around 5–14 years and a second peak in mid-adult life. The anatomy predicts the assessment findings. Optic chiasm compression disrupts crossing nasal retinal fibres and classically causes bitemporal hemianopia. Pituitary or stalk involvement produces deficiencies across several hormone axes. Hypothalamic involvement can impair satiety, temperature regulation, sleep, memory, behaviour, and thirst. Superior extension may obstruct...