Incidence: 3–4% of all intracranial neoplasms; 15% of supratentorial + 50% of suprasellar tumors in children; most common suprasellar mass

Origin: from epithelial rests along vestigial craniopharyngeal duct + primitive buccal epithelium (Rathke cleft cells within intermediate lobe of pituitary gland)

Path: cystic (rich in liquid cholesterol) / complex / solid

Age: from birth–7^th decade; M >F; bimodal age distribution with age peaks in 1^st–2^nd decade (75%) and in 4^th–6^th decade (25%)

• diabetes insipidus ← compression of pituitary gland
• growth retardation ← compression of hypothalamus
• bitemporal hemianopia ← compression of optic nerve chiasm
• headaches from hydrocephalus ← compression of foramen of Monro / aqueduct of Sylvius

Location: anywhere along infundibular stalk from floor of 3^rd ventricle to pituitary gland

1. suprasellar (20%)
2. intrasellar (10%)
3. intra- and suprasellar (70%)
   Ectopic craniopharyngioma:
4. floor of anterior 3^rd ventricle (more common in adults)
5. sphenoid bone

Skull films:

• normal sella (25%)
• enlarged J-shaped sella with truncated dorsum
• thickening + increased density of lamina dura in floor of sella (10%)
• extensive sellar destruction (75%)
• curvilinear / flocculent / stippled calcifications / lamellar ossification; calcifications seen in youth in 70–90%, in adults in 30–40%

CT:

• multilobulated inhomogeneous suprasellar mass
• solid (15%) / mixed (30%) / cystic lesion (54–75%) [cystic appearance ← cholesterol, keratin, necrotic debris with higher density than CSF]
• enhancement of solid lesion, peripheral enhancement of cystic lesion
• marginal hyperdense lesion (calcification / ossification) in 70–90% in childhood tumors + 30–50% of adult tumors
• ± obstructive hydrocephalus
• extension into middle >anterior >posterior cranial fossa (25%)

MR (relatively ineffective in demonstrating calcifications):

• hyperintense (mostly), but also iso- / hypointense on T1WI (variability ← hemorrhage / cholesterol-containing proteinaceous fluid)
• markedly hyperintense on T2WI
• heterogeneous enhancement of solid components + cyst wall

Angio:

• usually avascular
• lateral displacement, elevation, narrowing of supraclinoid segment of ICA
• posterior displacement of basilar artery

DDx:

1. Epidermoid (no contrast enhancement)
2. Rathke cleft cyst (small intrasellar lesion)
3. Hemorrhagic pituitary macroadenoma (fluid-fluid level)