Craniopharyngioma
Two types: adamantinomatous (paediatric‑predominant; calcified; sticky; “machinery/motor oil” cysts) and papillary (adult‑only; smoother; often third‑ventricular; calcification uncommon). Typically suprasellar with sellar extension, high recurrence risk, especially after subtotal resection so long‑term imaging follow‑up is standard.
Locally aggressive with high morbidity but benign oral ectodermal tumour from Rathke’s pouch remnants.
Patients can present with visual disturbance, headache, behavioural change and endocrine dysfunction (growth failure, delayed puberty, hypopituitarism, diabetes insipidus, hypothalamic obesity).
Adamantinomatous type
Majority overall; most common non‑glial suprasellar tumour in children.
- Multiloculated cysts with cholesterol crystals and wet keratin → “machinery oil” fluid.
- Irregular, adherent margins; often stick to the hypothalamus/optic chiasm.
- Classic bimodal age distribution (large peak 5–15 y; smaller peak middle‑aged adults).
Papillary type
Adult‑only (30–60 y).
- More discrete, encapsulated solid/cystic mass; rare calcification.
- Frequently arises in/extends to the third ventricle.
- Molecular: often BRAF V600E‑mutant (therapeutic implications in recurrence).
Location & size
- Primarily suprasellar; intrasellar‑only is uncommon.
- May be largely/entirely third ventricular (especially papillary).
- Lesions can be large; mass effect on chiasm and hydrocephalus possible.
Imaging features
May see a separate, compressed pituitary gland below a predominantly suprasellar mass.
CT
Adamantinomatous “rule of 90” teaching pearl:
- ~90% mixed cystic/solid (papillary more often solid).
- ~90% calcified (coarse/eggshell); papillary rarely calcified.
- ~90% enhance (solid parts/capsule).
MRI
- Cyst content: variable; T1 hyperintense pockets typical from cholesterol/protein (the “machinery oil” sign). T2 variable by protein/haemorrhage.
- Solid components/capsule: enhance; look for lobulated mural/solid tissue.
- Calcification: blooming/signal voids on GRE/SWI.
- Optic tract hyperintensity on T2/FLAIR is common and usually reflects oedema, not tumour invasion.
- Pituitary stalk: may be displaced or thickened; hypothalamic involvement is prognostically relevant.
Management
- Surgical debulking/resection when symptomatic or threatening vision; maximal safe resection; avoid hypothalamic devastation if possible
- Adjuvant radiotherapy often used for residual/recurrent disease.
- Targeted therapy can be considered in papillary (BRAF‑mutant) recurrence under multidisciplinary care.
Recurrence / Follow‑up
- Tends to recur after surgery; risk relates to residual tumour and hypothalamic involvement.
- Requires long‑term clinical + MRI follow‑up (years), adjusted to local protocol and extent of resection.
Differentials
Child suprasellar mass
- Rathke’s cleft cyst: midline rim‑only enhancement, non‑enhancing “waxy” intracystic nodule, calcification rare; often smaller and less aggressive interface.
- Cystic/non‑functioning adenoma: often off‑midline/asymmetric with enhancing mural/solid tissue; can show fluid–fluid levels.
- Arachnoid cyst: CSF signal on all sequences; no enhancement, no nodule.
- Epidermoid: insinuating margins; diffusion restriction.
- Optic pathway glioma
- Germinoma
T1‑bright cyst alone is not specific. Correlate with calcification and solid enhancement. If there’s no solid component and a classic waxy intracystic nodule, reconsider RCC. Restricted diffusion argues for epidermoid, not CP.
