Craniopharyngioma — Essay Answer for ENT Postgraduate Examination

Introduction

Epidemiology

• Accounts for 1%–5% of all intracranial tumours and 3%–5% of all paediatric brain tumours
• Most common non-glial, suprasellar tumour in children
• Bimodal age distribution: first peak at 5–15 years (adamantinomatous type); second peak in adults ≥65 years (papillary type)
• No significant sex predilection
• Incidence: fewer than 500 cases/year in adults in Western populations

Embryology & Pathogenesis

• Adamantinomatous type: near-universal (92–94%) CTNNB1 (β-catenin) gene mutations → aberrant nuclear β-catenin accumulation → activation of Wnt signalling pathway
• Papillary type: high rates (92–95%) of BRAF p.V600E mutations → activation of the RAS–MAP kinase pathway

Pathology

Gross Appearance

• Average diameter: 3–4 cm
• Usually suprasellar with or without intrasellar extension; 5% purely intrasellar
• May be encapsulated and solid, but more often cystic and multiloculated
• Cysts contain a characteristic thick, dark, cholesterol-rich, machine-oil–like fluid
• Tumour frequently encroaches on the optic chiasm, cranial nerves, and floor of the third ventricle

Histological Variants

Fig. Adamantinomatous craniopharyngioma: peripheral palisading (left) and characteristic compact lamellar "wet" keratin (right). — Robbins, Cotran & Kumar

Clinical Features

Onset

• Insidious — a 1–2 year history of slowly progressive symptoms is typical
• Symptoms arise from compression of adjacent structures

Symptom Triad

1. Raised intracranial pressure (headache, vomiting, papilloedema) — from hydrocephalus due to third ventricle obstruction
2. Visual disturbance — bitemporal hemianopia (chiasmal compression); may progress to optic atrophy
3. Endocrine dysfunction — hypopituitarism (most common endocrine manifestation):
   • Growth hormone deficiency → growth retardation, short stature (>70% of children at diagnosis)
   • Gonadotrophin deficiency → delayed puberty, amenorrhoea
   • TSH, ACTH, and LH/FSH deficiencies (panhypopituitarism)
   • Diabetes insipidus (hypothalamic/stalk involvement)
   • Hyperprolactinaemia (stalk effect — loss of dopaminergic inhibition)

Hypothalamic Involvement (particularly severe)

• Severe obesity (damage to satiety centres)
• Memory impairment, psychomotor slowing
• Altered sleep–wake rhythms
• Thermoregulatory dysfunction
• Loss of impulse control, behavioural changes

ENT-Relevant Presentation

• Rare ectopic presentation as a nasopharyngeal mass — can masquerade as hypertrophied adenoid tissue, especially in children
• Presents with nasal obstruction, epistaxis, or features mimicking adenoidal hypertrophy
• Must be considered in differential of nasopharyngeal lesions listed in Box 95.1 (Cummings Otolaryngology)

Investigations

Neuroimaging

• Suprasellar calcification in ~75% of cases — virtually pathognomonic in children
• Calcified, mixed cystic-solid mass
• Non-contrast CT best demonstrates calcification

• T1: Cystic component often hyperintense (due to proteinaceous/cholesterol-rich fluid); solid component isointense
• T2/T2 FLAIR: Cystic components hyperintense
• T1 + contrast: Enhancement of solid component and cyst wall
• Identifies relationship to optic chiasm, hypothalamus, and pituitary stalk
• MR spectroscopy: high lipid peaks
• Large tumours → hydrocephalus, forward displacement/stretching of optic nerves and chiasm

Fig. Craniopharyngiomas. (A–C) Large suprasellar calcified cystic–solid tumour encasing the basilar artery. (D–F) Smaller suprasellar calcified lesion with the optic chiasm draped over its top. — Grainger & Allison's Diagnostic Radiology

Endocrine Evaluation

• Basal pituitary hormone panel: GH/IGF-1, LH, FSH, TSH, free T4, ACTH/morning cortisol, prolactin
• Water deprivation test / paired plasma and urine osmolality (diabetes insipidus)
• Visual field assessment (Humphrey perimetry — bitemporal hemianopia)

Differential Diagnosis of Suprasellar Mass

• Pituitary adenoma
• Germinoma / dysgerminoma
• Rathke's cleft cyst (cuboidal epithelium; white mucoid fluid; no calcification)
• Meningioma
• Optic pathway glioma
• Langerhans cell histiocytosis
• Arachnoid cyst
• Hypothalamic hamartoma
• Nasopharyngeal carcinoma (ectopic craniopharyngioma mimicry)

Management

1. Surgery — Primary Treatment

• Preferred for subdiaphragmatic (intrasellar) tumours and small suprasellar extensions
• Associated with lower incidence of postoperative diabetes insipidus
• Endoscopic endonasal extended transsphenoidal approach increasingly used

• Subfrontal, pterional, or interhemispheric approaches
• Required for large suprasellar/third ventricular tumours

• Radical (gross total) resection: achieves best local control but risks profound hypothalamic damage → severe obesity, panhypopituitarism, visual loss, memory impairment, behavioural change
• Hypothalamic-sparing (limited) resection: less morbidity, similar or acceptable recurrence rates when combined with radiation; advocated by UK guidelines
• Surgical margins are deceptive — microscopic finger-like extensions are common; complete resection does not guarantee recurrence-free survival

2. Radiotherapy

• External beam radiotherapy (EBRT): extends progression-free survival after incomplete resection; long-term survival achievable with surgery + radiation
• Stereotactic radiosurgery (Gamma Knife): suitable for small residual/recurrent disease; good local control
• Intracavitary irradiation: ³²P or ⁹⁰Y instilled stereotactically into cystic component — effective for predominantly cystic tumours
• Intracavitary bleomycin: for cystic components following stereotactic aspiration
• Radiation dose typically 50–55 Gy in conventional fractionation
• Combined limited surgery + adjuvant radiotherapy: maximises quality of life while achieving >90% long-term survival in children

3. Targeted Molecular Therapy (Emerging)

• Papillary craniopharyngiomas with BRAF V600E mutation: BRAF inhibitors (vemurafenib, dabrafenib) ± MEK inhibitors (trametinib) have shown remarkable responses in case series and small studies
• Phase II trials underway combining BRAF + MEK inhibition
• Potentially transformative — may offer non-surgical cytoreduction pre-operatively or as primary treatment in unresectable cases
• Adamantinomatous type: drugs targeting β-catenin/Wnt pathway under development

4. Postoperative Endocrine Replacement

• Virtually all patients require lifelong hormone replacement following surgery:
  • Hydrocortisone (cortisol replacement)
  • Levothyroxine (thyroid replacement)
  • Sex steroids (oestrogen/testosterone)
  • GH replacement (especially in children)
  • Desmopressin (DDAVP) for diabetes insipidus
  • Management of hypothalamic obesity (dietary, behavioural, pharmacological measures)

5. Management of Hydrocephalus

• Ventriculoperitoneal (VP) shunting or external ventricular drain if hydrocephalus is severe
• Often resolves after tumour resection

Prognosis

• Overall survival: >90% at 10 years in children with combined modality treatment
• Recurrence rate: 25–50% after radical resection; higher after subtotal resection alone
• Main cause of morbidity: hypothalamic dysfunction (obesity, cognitive impairment, endocrine sequelae) — often more debilitating than the tumour itself
• Recurrence management: surgery + radiation, stereotactic radiosurgery, or targeted therapy (BRAF tumours)
• Quality of life is significantly impaired in many long-term survivors, primarily due to metabolic and neurocognitive sequelae

Summary Table

ENT-Specific Relevance

1. Differential diagnosis of nasopharyngeal masses — ectopic craniopharyngioma can arise anywhere along the Rathke pouch migratory path from the nasopharynx to the sella. Cases of extra-sellar craniopharyngioma masquerading as hypertrophied adenoid tissue in children have been documented (Cummings Otolaryngology).
2. Skull base surgery — transsphenoidal endoscopic approaches are performed by ENT-trained skull base surgeons in many centres. The expanded endonasal approach to the sella and suprasellar space is a core ENT skull base procedure.
3. Visual assessment — bitemporal field defects require collaboration with ophthalmology.
4. CSF rhinorrhoea — a recognised complication of transsphenoidal resection requiring ENT management.