Craniopharyngioma

Craniopharyngiomas are epithelial tumours derived from remnants of Rathke's pouch along the pituitary stalk. The 2021 WHO classification recognises adamantinomatous and papillary craniopharyngioma as separate tumour types^[1]. The adamantinomatous type affects children and adults, is driven by CTNNB1 (β-catenin) mutations, and is typically cystic with “machine-oil” fluid and calcification. The papillary type occurs almost exclusively in adults, is usually solid or mixed and non-calcified, and carries the BRAF V600E mutation in the large majority of cases^[2,3].

Presentations reflect the involved structures: visual field loss from chiasmal compression, headache and hydrocephalus from third-ventricular obstruction, and endocrine deficits (growth hormone deficiency and growth failure in children, hypogonadism, hypothyroidism, adrenal insufficiency, and diabetes insipidus). Hypothalamic involvement produces obesity, disturbed sleep and temperature regulation, and behavioural and memory problems, which are the main determinants of long-term quality of life^[3].

CT shows calcification, which is highly suggestive of the adamantinomatous type. MRI defines the solid and cystic parts, the position relative to the chiasm, stalk and third-ventricular floor, and the degree of hypothalamic involvement. The tumour is classified by its relation to the diaphragma sellae and the stalk (sellar, preinfundibular, transinfundibular, retroinfundibular), which strongly influences the choice of approach. Full endocrine testing, including cortisol, and formal visual fields and acuity, are obtained before surgery; corticosteroid cover is given if adrenal insufficiency is suspected.

Puget and colleagues graded hypothalamic involvement on preoperative MRI as grade 0 (none), 1 (hypothalamus displaced or abutted) or 2 (hypothalamus no longer visible, i.e., invaded), and showed that avoiding hypothalamic injury in grade 2 tumours reduced postoperative hypothalamic morbidity^[4].

Management is individualised and best decided by a multidisciplinary team. Gross-total resection is appropriate when the tumour can be separated from the hypothalamus and visual pathways; when the hypothalamus is invaded, a planned subtotal resection followed by radiotherapy (including proton therapy) gives similar tumour control with less morbidity^[3,4]. Predominantly cystic tumours may be managed by cyst drainage through an Ommaya reservoir, with or without intracystic therapy. For papillary BRAF V600E-mutant tumours, combined BRAF–MEK inhibition produced major tumour shrinkage in most patients in a phase 2 trial, and is now an option before or instead of surgery^[5].

• Endoscopic endonasal (extended transtuberculum–transplanum) approaches suit midline sellar, preinfundibular and transinfundibular tumours and give a direct view of the chiasm's undersurface and the stalk^[6].
• Transcranial routes (pterional, orbitozygomatic, supraorbital, subfrontal or translamina terminalis) suit tumours with lateral or high third-ventricular extension; the transcallosal or transcortical route is used for purely intraventricular tumours.
• Preserve the superior hypophyseal arteries supplying the chiasm, and preserve the pituitary stalk when feasible.
• Sharp dissection at the tumour–hypothalamus interface; accept residual where the plane is lost.
• Reconstruct the skull base with a vascularised flap after extended endonasal surgery^[7].

Diabetes insipidus and panhypopituitarism are common after radical resection and require lifelong replacement. Other risks include visual worsening, CSF leak, vascular injury, and hypothalamic obesity, which can be severe. Recurrence is frequent after subtotal resection without radiotherapy. Survival is high but quality of life depends on hypothalamic integrity, so the operation that best preserves the hypothalamus is usually the right one^[3].